CHAPTER 80 MORPHOLOGY OF LYMPHOCYTES AND PLASMA CELLS
CHAPTER 80 MORPHOLOGY OF LYMPHOCYTES AND PLASMA CELLS
STEPHEN M. BAIRD
Definition and History
Microscopy and Histochemistry of Normal Blood Lymphocytes
Transmission Electron Microscopy and Cytochemistry
Scanning Electron Microscopy
Morphologic Changes Associated with Activation
Microscopy and Histochemistry of Plasma Cells
Light Microscopy, Histochemistry, and Electron Microscopy
Antigens of Human Lymphocytes
Natural Killer Cells
Lymphocytes are a heterogeneous collection of cells that can be distinguished easily from other leukocytes by their characteristic morphology. However, this morphology is shared by all three major blood lymphocyte subsets, namely T cells, B cells, and natural killer (NK) cells. Although B cells can differentiate into plasma cells that have a distinctive morphology, most changes that occur in morphology during differentiation or activation are not unique to any one of the three major subgroups. Instead, other means are required to distinguish the major subsets and sub-subsets of lymphocytes. This has been achieved through the advent of monoclonal antibodies and the characterization of surface membrane antigens that are distinctive for each lymphocyte subset. This chapter describes the morphologic features that distinguish lymphocytes from other leukocytes and the membrane antigens that most commonly are used to distinguish the major lymphocyte subsets.
Acronyms and abbreviations that appear in this chapter include: ADCC, antibody-dependent cell-mediated cytotoxicity; CD, clusters of differentiation; LFA-3, lymphocyte-function–associated antigen-3; MHC, major histocompatibility complex; N-CAM, neural adhesion protein; NK, natural killer; PAS, periodic acid–Schiff; TCR, T-cell antigen receptor.
DEFINITION AND HISTORY
Lymphocytes and plasma cells first were described morphologically in 1774 and 1875, respectively.1,2 Investigations of these cells from then until the 1960s primarily were to further define their morphology. Subsequently, lymphocytes were found to make immunoglobulins and to be necessary for cell-mediated immunity.3,4,5,6 and 7 With the advent of monoclonal antibodies and flow cytometry, the refinement of in vitro functional assays, and the application of molecular techniques, there have been major advances in the understanding of lymphocytes. Membrane antigens have been identified that assist in the designation of lymphocyte subsets and function. Three major blood lymphocyte subsets have been identified: T lymphocytes, B lymphocytes, and NK cells. Further, there are small numbers of circulating hematopoietic stem cells that resemble lymphocytes and that are capable of differentiating into any one of the various lymphocyte subsets.
MICROSCOPY AND HISTOCHEMISTRY OF NORMAL BLOOD LYMPHOCYTES
Classic studies of blood and tissues have demonstrated populations of spherical and/or ovoid cells that are from 6 to 15 µm in diameter when flattened on glass slides.4 Some of these studies described small lymphocytes, which are 6 to 9 µm in diameter, and large lymphocytes, which have a diameter of 9 to 15 µm. There are increased numbers of circulating large lymphocytes in patients with acute viral illnesses and in certain genetic immunologic deficiencies, particularly the Wiskott-Aldrich syndrome. Normal adults have a mean absolute number of circulating small lymphocytes of 2.5 × 109/liter (range of 1.5 to 4.0), or 35 percent of the total leukocytes (with a range of 20 to 50 percent).
The typical small lymphocyte as observed with Romanovsky polychromatic stains (e.g., Giemsa or Wright) has an ovoid or kidney-shaped nucleus that stains purple, has densely packed nuclear chromatin, and occupies about 90 percent of the cell area (see Plate XX-4). There is a small rim of cytoplasm that stains light blue. Although nucleoli rarely are observed in Giemsa-stained films, they can be demonstrated with methyl green-pyronine stains. Cytoplasmic basophilia is related to RNA content. The cytoplasm of some lymphocytes, particularly large lymphocytes, contains a number of coarse pink granules, usually 5 to 15 per cell, and occasional clear vacuoles. Cytoplasmic glycogen is detected with periodic acid–Schiff (PAS) and methenamine-silver techniques. A number of enzymes, including phosphorylase, acid hydrolases, nucleases, and mitochondrial enzymes, are in the lymphocyte cytoplasm.8 Peroxidase reactions are negative in lymphocytes.9
In a normal adult about 3 percent of blood lymphocytes are large granular lymphocytes10 (see Plate XX-3). These cells are a mixed population consisting of NK cells and some of the CD8 subset of mature T cells. The majority of mature T lymphocytes, however, show a localized “dot” staining pattern for acid phosphatase, acid and neutral nonspecific esterases, b-glucuronidase, and N-acetyl-b-glucosaminidase.11,12 and 13 B lymphocytes either lack esterase and acid phosphatase or show scattered granular staining.
Enzymes in the purine salvage pathways are expressed differently in lymphocyte subsets. The enzyme 5′-nucleotidase is detectable on plasma membranes of both B and T cells. In contrast, more adenosine deaminase and purine nucleoside phosphorylase are present in the cytoplasm of T cells than in the cytoplasm of B cells.14,15 Terminal deoxynucleotidyl transferase is present in cortical thymocytes, undifferentiated stem cells, and the malignant cells of acute lymphoid leukemias.16,17
Active movement of lymphocytes is studied by phase-contrast, or interference-contrast, microscopy. Lymphocytes move slowly with a “hand mirror” appearance. Cytoplasmic spreading does not occur. However, during cell movement a thickening occurs in the cytoplasmic rim (the Hof region), a region that houses most of the cell’s organelles, including the Golgi. Lymphocytes from patients with chronic lymphocyte leukemia have decreased movement.18
TRANSMISSION ELECTRON MICROSCOPY AND CYTOCHEMISTRY
As visualized by transmission electron microscopy,19,20,21 and 22 the circulating lymphocyte measures about 5 µm in diameter. The nucleus has an abundance of electron-dense, condensed heterochromatin, a feature characteristic of nonproliferating cells. The nucleoli are round in section, about 1.0 to 1.5 µm in diameter, and composed of three distinct and concentrically arranged structural units: the central region or agranular zone; the middle, fibrillar region; and the granular zone, which contains intranucleolar chromatin. The lymphocyte’s nuclear membrane contains nuclear pores and a perinuclear space.
The cytoplasmic organelles of the lymphocytes are characteristic of eukaryotic cells.19,20,21 and 22 Some organelles, like the Golgi zone, are poorly developed. The cytoplasm contains free ribosomes, occasional ribosome clusters, and strands of rough-surfaced endoplasmic reticulum (Fig. 80-1). Centrioles, mitochondria, microtubules (diameter of approximately 0.25 µm), and microfilaments (diameter of about 0.07 µm) are present in the cytoplasm adjacent to the cell membrane. The cytoplasm also contains lysosomes, which are about 0.4 µm in diameter, are electron-opaque, and contain classic lysosomal enzymes (e.g., acid phosphatase, b-glucuronidase, and acid ribonuclease).8 The lymphocyte plasma membrane stains with colloidal iron, a marker for membrane sialic acid. Lymphocyte cell membranes and cell coat glycoproteins are shown with other electron-dense markers including phosphotungstic acid, lanthanum colloid, and ruthenium red.
FIGURE 80-1 (A) Electron micrograph of normal human blood lymphocytes. Organelles are labeled in (B). (×12,000) (b) Diagrammatic representation of normal blood lymphocyte.
SCANNING ELECTRON MICROSCOPY
Scanning electron microscopy provides three-dimensional information.23 However, the resolution achieved with scanning electron microscopy, about 0.1 µm, is considerably less than that possible with transmission electron microscopy, generally 0.002 to 0.0039 µm. Normal blood lymphocytes, washed and collected onto silver membranes and fixed in glutaraldehyde, have a spherical topography with varying numbers of stubby or fingerlike microvilli (Fig. 80-2).24,25 In contrast, monocytes are much larger, have few microvilli, and display ruffled membranes and ridgelike profiles. T lymphocytes have smaller numbers of microvilli than B lymphocytes.24,25 However, the surface morphology of B lymphocytes is heterogeneous. Many B cells have moderate to markedly villous surfaces, but about 10 to 20 percent of B cells are smooth with few microvilli and thus are indistinguishable from most T lymphocytes.26 Furthermore, human blood lymphocytes fixed in suspension appear uniformly covered with short microvilli, and no differences between T and B cells are demonstrable.
FIGURE 80-2 Scanning electron micrograph of normal blood lymphocytes separated by the Ficoll-Hypaque method. Cells show varying numbers of microvilli. (×5000) (Fig. 80-3, Fig. 80-4, and Fig. 80-5 provided by Dr. Aaron Polliack of the Department of Hematology, Hebrew University Hadassah Medical School, Jerusalem, Israel.)
FIGURE 80-3 Transmission electron micrograph of lymphocyte from normal individual incubated with PHA for 3 days. The transformed cell has a large Golgi zone (G) and many ribosomal aggregates (arrows), and the nucleus is euchromatic. (×7500)
FIGURE 80-4 Transmission electron micrograph of plasmacytoid cell present in culture of lymphocytes from a patient with chronic lymphocytic leukemia incubated with pokeweed mitogen for 7 days. The nucleolus (N) and rough-surfaced endoplasmic reticulum (arrows) are evident. (×9000) (From Cohnen, Douglas, Konig, et al: Pokeweed mitogen response of lymphocytes in chronic lymphocytic leukemia. Blood 42:591, 1973, with permission.)
FIGURE 80-5 This is a diagram of lymphocyte activation that displays the relationship of cell-cycle phases (G0, G1, S, and M) with changes in cell metabolism and cell function. A lymphocyte may become an effector cell or a memory cell in G0 after having traversed the cell cycle. (Klein, Immunology, p 40. Blackwell, Cambridge, MA, 1990, with permission.)
MORPHOLOGIC CHANGES ASSOCIATED WITH ACTIVATION
Lymphocyte stimulation is associated with a complex sequence of morphologic and biochemical events, culminating in the transformation of small lymphocytes into blast or plasmacytoid cells (Fig. 80-3 and Fig. 80-4). Plant lectins, bacterial products, polymeric substances, and enzymes stimulate lymphocyte mitosis. Such agents are called mitogens. Some mitogens are specific for either B cells or T lymphocytes, whereas others stimulate both. The responses of specific lymphocyte subpopulations to various mitogens are complex.33 Nucleolar changes become evident as early as 4 h after exposure to phytomitogens (e.g., phytohemagglutinin, which stimulates T cells). These morphologic changes consist of increases in nucleolar size and in the number and concentration of granules in the granular zone. This is followed by an increase in fibrillar zones and increased intranucleolar chromatin. Nucleolar chromatin becomes more electron-lucent or dispersed. Electron microscopic autoradiography demonstrates that tritiated thymidine, incorporated into newly synthesized DNA, is spread throughout the nucleoplasm but is most concentrated at the nuclear membrane. From 48 to 72 h following the addition of phytohemagglutinin there is an increase in size of the cytoplasm. In addition, the cytoplasm contains an increase in the number of ribosomal clusters and more rough-surfaced endoplasmic reticulum. The transformed cell (lymphoblast) has increased numbers of lysosomes and a larger Golgi complex with more components.19,20,21 and 22 Under some circumstances (e.g., cultures of human lymphocytes stimulated for 7 to 10 days with pokeweed mitogen), some cells may form well-developed Golgi and plasmacytoid features.34 Similar plasmacytoid cells are observed in antigen-stimulated lymph nodes, during graft rejection in vivo, and in some in vitro systems, including the mixed lymphocyte culture.
Following stimulation with antigen or mitogens the lymphocyte enters the cell cycle. The cell-cycle phases and accompanying genetic or morphologic changes are summarized in Fig. 80-5. These parallel genetic and morphologic alterations are necessary correlates of the cell-cycle phases. The fate and function of lymphocytes that traverse the cell cycle may be divided into two pathways. Some lymphocytes may undergo several mitotic cycles and then return to the Go phase, indistinguishable in morphology from the original nonactivated cells. A separate subset of lymphocytes may become memory cells, programmed to remember the stimulating antigen and thus more rapidly respond to reexposure to the original antigen. Finally a small number of lymphocytes are destined to become terminally differentiated lymphocytes, such as plasma cells or cytotoxic T cells.
MICROSCOPY AND HISTOCHEMISTRY OF PLASMA CELLS
Plasma cells derive from small B lymphocytes after antigenic stimulation and T-cell help. Several sequential mitotic divisions occur during cellular differentiation from the resting lymphocyte to the plasmablast to the immature plasma cell. Immature plasma cells also can undergo successive waves of mitosis in the medullary cords of lymph nodes in response to antigen.37 Cell transfer experiments demonstrated that these transformed cells later mature into antibody-producing plasma cells.38
Pokeweed mitogen induces B lymphocytes to transform into plasma cells after 7 to 10 days’ culture.39 These plasma cells infrequently contain large electron-dense inclusions, which may measure 2 to 3 µm in diameter (Russell bodies) (Fig. 80-6).40 Russell bodies, cytoplasmic immunoglobulin in the endoplasmic reticulum, sometimes are dissolved during the Giemsa staining procedure. They usually occur in pathologic states but may be found in normal lymph nodes or marrow. When cytoplasmic immunoglobulin becomes detectable, the same immunoglobulin isotype is present in the cytoplasm as on the cell membrane.
FIGURE 80-6 Intranuclear electron-dense bodies (Russell bodies) (RB) in plasma cell from the marrow of a patient with multiple myeloma. (×7000)
LIGHT MICROSCOPY, HISTOCHEMISTRY, AND ELECTRON MICROSCOPY
When treated with a polychrome stain, the mature plasma cell has a characteristic basophilic cytoplasm and an eccentric nucleus. The nuclear polarity is attributable to a large paranuclear zone, which corresponds to the Golgi apparatus. The typical mature plasma cell spread on a slide is usually round or oval and has a diameter from 9 to 20 µm, with a mean cell diameter of 14.4 µm and a mean nuclear diameter of 8.5 µm27 (see Plate XXI-1). The nuclear heterochromatin is coarse and distributed in a pattern that, in paraffin sections, sometimes resembles the spokes of a wheel (cartwheel nucleus). Plasma cells with two or more nuclei occasionally may be seen in the marrow of normal individuals. The nucleus stains blue-green with methyl green. The cytoplasm is characterized by its intense affinity for cationic dyes. The cytoplasm, basophilic due to ribonucleoprotein, stains selectively with methyl green-pyronine; it stains red with pyronine due to its high content of ribonucleoprotein (pyroninophilia). The cytoplasm also stains with several basic dyes, including toluidine blue and azures.
Plasma cells that are found in patients with certain diseases may have different histochemical properties. These cells may have a larger size and contain cytoplasmic inclusions that may be observed with PAS stains.28 In hemochromatosis and hemosiderosis, plasma cells may contain hemosiderin when examined by electron microscopy.29 Other cytochemical features include absence of peroxidase and nonspecific esterase. Plasma cells are strongly positive for b-glucuronidase and for mitochondrial enzyme markers.30 Plasma cell size and morphology may be altered substantially in multiple myeloma and macroglobulinemia (see Plate XXI-4, Plate XXI-5, Plate XXI-6, Plate XXI-7, Plate XXI-8 and Plate XXI-9). Cells with 2 or 3 nuclei may be seen, even in adults without plasma cell dyscrasias. Under some circumstances amyloid inclusions have been detected by electron microscopy in plasma cells.31
By electron microscopy the plasma cell is packed with a rough-surfaced endoplasmic reticulum that has numerous attached ribosomes. There is a large circumscribed Golgi zone that forms a paranuclear halo when observed by light microscopy. The nucleus has dense areas of heterochromatin. The Golgi zone contains lamellae, vesicles, vacuoles, and a number of granules. Between the strands of endoplasmic reticulum there are mitochondria (Fig. 80-7).32
FIGURE 80-7 (A) Electron micrograph of mature plasma cells in normal human lymph node. (×9000) (B) Diagrammatic representation of normal plasma cell labeling the organelles.
ANTIGENS OF HUMAN LYMPHOCYTES
Human blood lymphocytes possess an array of different membrane antigens. Standardization of monoclonal antibody reagents by identifying clusters of differentiation (CD) and the advent of flow cytometry have facilitated detection of lymphocyte subsets (see Chap. 13). The following sections list those surface antigens and morphologic features that help define the major human lymphocyte subsets.
Table 80-1 summarizes the expression of CD antigens on cells of the B-lymphocyte lineage, including committed progenitor B cells and pre-B cells. These cells, and the maturation stages that they represent, are discussed in Chap. 82. Also presented in Table 80-1 are antigens that are expressed or are increased upon B-cell activation. The physiology, structure, and distribution of each of the CD antigens listed in Table 80-1 are presented in Chap. 13 (see Table 13-1).
TABLE 80-1 B-LYMPHOCYTE ANTIGENS USED IN CLINICAL MEDICINE
Of the B cell-associated antigens listed in the first column of Table 80-1, only a few are restricted to cells of the B lineage (see Chap. 13). Of these, only CD20, CD79a, and CD79b are not found on other cell types. The latter two antigens associate with Ig to facilitate surface Ig expression and surface-Ig–mediated signal transduction and are expressed only by cells that produce Ig, an exclusive function of B lymphocytes and plasma cells (see Chap. 15 and Chap. 83). CD19 is restricted mostly to B cells but may be expressed weakly by follicular dendritic cells. This antigen, however, is expressed by B cells at all stages of maturation, including the committed B-cell progenitor. As such, it is the best-defined pan-B cell surface antigen. Cytoplasmic CD22 is perhaps the broadest mature B-cell marker.
In addition to the CD antigens, B cells express the three major histocompatibility complex (MHC) class II antigens (DR, DP, DQ). These antigens are heterodimers of a heavy chains and b light chains that are encoded by genes within the D complex of the HLA complex (see Chap. 138).
B-1 B CELLS
A subset of normal B cells express CD5,45 a 67-kDa transmembrane glycoprotein46 that is expressed by T cells (see Chap. 13). These cells are designated CD5 B cells, or, more recently, B-1 B cells.47 B-1 B cells do not express other T-cell markers but do express all other pan-B-cell surface antigens.48 B-cell expression of CD5 can be modulated by various agents.49,50 B-1 B cells are found in umbilical cord blood,51 adult blood, the pleura and peritoneum, and all major secondary lymphoid organs but are rare in the marrow.52 These cells apparently are enriched for cells that spontaneously produce polyreactive autoantibodies.53,54 and 55 They are the cells that are clonally expanded in chronic lymphocytic leukemia (see Chap. 98).
Most B-cell differentiation antigens are not expressed by the mature plasma cell, including surface immunoglobulin and HLA class II antigens56 (see Table 80-1). Of the cells of the B lineage, plasma cells are distinctive in that they express CD28 and PCA-1. CD28 is found on marrow plasma cells and myeloma cell lines.57 PCA-1 also is found on human plasma cells58 and may function as a threonine-specific protein kinase.59 This latter function may assist in phosphorylation of secretory proteins. PCA-1 also is present at low density on granulocytes and monocytes. In contrast to mature B lymphocytes, plasma cells do not bear surface Ig but express CD38 and very high levels of CD43 and CD85 (see Table 80-1).
CD1 is a family of three membrane glycoproteins, CD1a, CD1b, and CD1c, of 49, 45, and 43 kDa, respectively, that is found on all cortical thymocytes (see Chap. 13). CD1 also can be expressed on monocytes following activation and on Langerhans cells.60 CD1 has a structural relationship to HLA class I and class II proteins. This structural association suggests that CD1 is involved in T-cell interaction with accessory/antigen-presenting cells, perhaps presenting hydrophobic antigens such as lipids.
This T-cell antigen is expressed early in T-cell development. It is a 50-kDa surface glycoprotein that facilitates T-lymphocyte target cell interactions and T-lymphocyte activation.61 Lymphocyte-function-associated antigen-3 (LFA-3) (CD58) is a ligand for CD2 (see Chap. 13 and Chap. 84). Cross-linking CD2 may activate T cells through a pathway that is distinct from that used by the T-cell receptor for antigen. This may result in augmentation of the immune response in the absence of additional antigenic stimulation. Since anti-CD2 monoclonal antibodies activate early T-lymphocyte progenitors, CD2 antigen probably is a receptor used in the activation of thymocytes prior to appearance of a functional T-cell receptor.62
CD3 is expressed by early thymocytes and mature T cells.63 It is tightly linked to the T-cell receptor (see Chap. 84). The CD3 molecule serves as a signal transduction unit after T-cell receptor activation. In addition, this antigen frequently is expressed on T-cell acute lymphoblastic leukemia.
CD5 is found on all T cells. It appears early in T-lymphocyte ontogeny.64 CD5 also may be detected on a subset of blood and cord B cells.
CD7 is a 40-kDa glycoprotein that is expressed very early in T-cell ontogeny.65 The antigen is lost during the terminal stage of T-cell maturation. The function of CD7 is not known. CD7 also is expressed on monocytes or natural killer cells.66
CD4 AND CD8
CD4 is first expressed on thymocytes along with CD8 (see Chap. 82 and Chap. 84). CD4, a member of the immunoglobulin supergene family, is a single-chain transmembrane glycoprotein.67 CD8 is a homodimeric transmembrane glycoprotein of 34 kDa.68 Each molecule also is associated with the T-cell–specific tyrosine kinase p56.69 CD4 and CD8 act as coreceptors during T-cell activation by antigen (see Chap. 84). CD4 also is a coreceptor for the human immunodeficiency virus70 (see Chap. 89), along with CCR5 or CXCR4.
CD25 originally was defined as a component of the interleukin-2 receptor (IL-2R).71 This antigen is expressed on activated T and B cells. CD25 also is found on thymocytes and monocytes. The IL-2 receptor is made of three distinct proteins [a chain (CD25), b chain (CD122), and g chain, also a component of the receptors for IL-4, 7, and 9]. When bound to the a chain alone, IL-2 binds with higher affinity to the IL-2R b chain. This then results in formation of a high-affinity complex of IL-2 bound to both IL-2R a and b chains.73 The g chain is involved in signaling to the cell after IL-2 binding. IL-2 binding to the high-affinity receptor signals T cells to proliferate and differentiate into specific effector T cells (e.g., helper T or cytotoxic T cells).
CD45 is tyrosine-specific phosphatase.74 It is expressed by virtually all hematopoietic cells. However, different isoforms exist due to alternative splicing of the CD45 transcript and differential glycosylation.75 These different isoforms of CD45 are expressed differentially by different cell subsets (see Chap. 84). CD4+ helper T cells can be divided into functionally disparate subsets based on their expression of the different CD45 isoforms and CD29 (the VLA b chain). Naive CD4+ helper T cells are CD45RA+ and express low levels of CD29. These CD4+ T cells can induce CD8+ T cells to downregulate B-cell IgG synthesis.76 After activation, T-cell expression of CD45RA is diminished, but that of CD29 and CD45RO (a lower-molecular-weight isoform of CD45) is enhanced.77 CD4+ CD45RO+ CD29 high-affinity T cells are called memory-helper T cells, in that they apparently facilitate induction of B-cell IgG synthesis in response to secondary challenge with antigen. In addition, CD45 is necessary for activation of either CD4+ T cells or CD8+ T cells. T cells that lack expression of CD45 do not respond well to various activation stimuli.77
CD28 is a 44-kDa homodimer that is expressed on resting T cells. CD28 is a surface receptor for a cyclosporine-resistant T-cell signal-transduction pathway.78 CD28 binds the CD80 (B7/BB1) antigen expressed by activated B cells and professional antigen-presenting cells79 (see Chap. 84). This interaction provides a second costimulatory signal to T cells that are activated by the cross-linking of their T-cell antigen receptors in response to specific interactions with antigenic peptide bound to the major histocompatibility antigens expressed by antigen-presenting cells.80,81 Without this second costimulatory signal, the T cell may be induced into anergy.82 In this state the T cells fail to respond to the antigen(s) presented by the antigen-presenting cell because of a block in IL-2 gene expression.83
The T-cell antigen receptor (TCR) is present on all mature T cells and on developing immature thymocytes (see Chap. 84). The TCR may have unique determinants that are found on all T cells within a given T-cell clone. It is expressed by most T-cell lymphomas.
NATURAL KILLER CELLS
The NK cell is defined as an effector cell that is not MHC-restricted and has the capacity for spontaneous cytotoxicity toward various target cells (see Chap. 85). The large granular lymphocyte was identified as being the blood cell responsible for NK-cell function because these cells, when enriched by sedimentation, accounted for almost all the blood NK-cell activity.84 However, not all NK cells have large granular lymphocyte morphology.
Large granular lymphocytes have a unique morphology (see Plate XX-3). These cells typically have round or indented nuclei and abundant pale cytoplasm containing a few coarse pink granules (1.0 to 2.0 µm in diameter).85 Large granular lymphocytes have membrane-bound granules that stain for acid hydrolases, including acid phosphatase, a napthyl acetate esterase, and b glucuronidase. These granules may be related to the cytolytic capacity of these cells. These cells do not express surface immunoglobulin and lack adherent or phagocytic properties. They may form rosettes with sheep erythrocytes and express immunoglobulin Fc receptors.25,86 Despite their relative morphologic homogeneity, they comprise several subpopulations with distinct phenotypes. NK cells express class I but not class II antigens of the MHC. Human NK cells characteristically express CD16 (FcgRIII) and CD56, but not CD3.87,88 CD16 (FcgRIII) is a low-affinity receptor that binds to IgG that is bound specifically to antigens present on cells targeted for destruction in antibody-dependent cell-mediated cytotoxicity (ADCC). CD16 is expressed on all NK cells, neutrophils, and tissue macrophages. CD56 is the neural adhesion protein (N-CAM) and is seen on most NK cells, albeit at low density.89 This 200-kDa protein is expressed at higher levels following activation.
NK cells have some T-cell antigens on their cell membrane, including CD8, found on approximately 30 to 50 percent of NK cells; CD2, present on about half of all NK cells; and CD38, present at low density on most NK cells. However, NK cells do not express CD4.90 Upon activation, NK cells express increased levels of CD25, CD56, and class II antigens of the MHC. Three cytokines that can activate NK cells are IL-2, interferon-alpha, and IL-12. IL-2 also can induce NK cells and some T cells to differentiate into lymphokine-activated killer cells in vitro (see Chap. 85).
Hewson W, Johnson J: No. 72, Pauls Church Yard London, 1774, in Lymphatics, Lymph and Lymphomyeloid Complex, 3d ed, edited by JM Yoffey, FC Courtice, p. 3. Harvard, Cambridge, MA, 1970.
Ramon Y Cajal S: Manual de Anatomia Pathologica General. Intr. de la Casa provincial de Caridad, Barcelona, 1890.
Everett NB, Caffey RW, Rieke WO: Recirculation of lymphocytes. Ann NY Acad Sci 113:887, 1964.
Ford WL, Gowans JL: The traffic of lymphocytes. Semin Hematol 6:67, 1969.
Nossal GJV, Makela O: Elaboration of antibodies by single cells. Ann Rev Microbiol 16:53, 1962.
Miller RG: Physical separation of lymphocytes in the lymphocyte structure and function, in Immunology Series, edited by JJ Marchalonis, vol 5, p 205. Dekker, New York, 1977.
Ackerman GA: Structural studies of the lymphocyte and lymphocyte development, in Regulation of Hematopoiesis, edited by AS Gordon, vol 2, p 1297. Appleton Century Crofts, New York, 1970.
Brottinger G, Hirschhorn R, Douglas SD, Weissmann G: Studies on lysosomes: XI. Characterization of a hydrolase-rich fraction from human lymphocytes. J Cell Biol 37:394, 1968.
Yam LT, Li CY, Crosby WH: Cytochemical identification of monocytes and granulocytes. Am J Clin Pathol 55:283, 1971.
Timonen T, Ortaldo JR, Herberman RB: Characteristics on human large granular lymphocytes and relationship to natural killer and K cells. J Exp Med 153:569, 1981.
Bevan A, Burns GF, Gray L, Cawley JC: Cytochemistry of human T-cell subpopulations. Scand J Immunol 11:223, 1980.
Basso G, Cocito MG, Semenzato G, et al: Cytochemical study of thymocytes and T lymphocytes. Br J Haematol 44:577, 1980.
Machin GA, Halper JP, Knowles DM: Cytochemically demonstrable b-glucuronidase activity in normal and neoplastic human lymphoid cells. Blood 56:1111, 1980.
Tung R, Silber R, Quagliata F, et al: ADA activity in chronic lymphocytic leukemia—relationship to B- and T-cell subpopulations. J Clin Invest 57:756, 1976.
Rowe M, deGast GG, Platts-Mills TA, et al: 5′-nucleotidase of B and T lymphocytes isolated from human peripheral blood. Clin Exp Immunol 36:97, 1979.
Greenwood MF, Coleman MS, Hutton JJ, et al: Terminal deoxynucleotidyl transferase distribution in neoplastic and hematopoietic cells. J Clin Invest 59:889, 1977.
Bollum FJ: Terminal deoxynucleotidyl transferase as a hematopoietic cell marker. Blood 54:1203, 1979.
Cohen HJ: Human lymphocyte surface immunoglobulin capping: normal characteristics and anomalous behavior of chronic lymphocytic leukemic lymphocytes. J Clin Invest 55:84, 1975.
Douglas SD: Human lymphocyte growth in vitro: morphologic, biochemical and immunologic significance. Int Rev Exp Pathol 10:42, 1971.
Tanaka Y, Goodman JR: Electron Microscopy of Human Blood Cells. Harper & Row, New York, 1972.
Douglas SD: Electron microscopic and functional aspects of human lymphocyte response to mitogens. Transplant Rev 11:39, 1972.
Douglas SD, Cohnen G, Brittinger G: Ultrastructural comparison between phytomitogen transformed normal and chronic lymphocytic leukemic lymphocytes. J Ultrastruct Res 44:11, 1973.
Hayes TL: Scanning electron microscope techniques in biology, in Advanced Techniques in Biological Electron Microscopy, edited by JK Koehler, p 153. Springer, New York, 1973.
Polliack A, Lampen N, Clarkson BD, et al: Identification of human B and T lymphocytes by scanning electron microscopy. J Exp Med 138:607, 1973.
Polliack A, Fu SM, Douglas SD, et al: Scanning electron microscopy of human lymphocyte sheep erythrocyte rosettes. J Exp Med 140:146, 1974.
Polliack A, Hammerling V, Lampen N, DeHarven E: Surface morphology of murine B and T lymphocytes: a comparative study by scanning electron microscopy. Eur J Immunol 5:32, 1975.
Sachetti D: Le plasmacellule nel midollo osseo delluomo nella norma e nella pathologia: Richerche quantitative citometriche et auxologiche. Haematologica (Pavia) 35:13, 1951.
Quaglino D, Torelli V, Sauli S, Mauri C: Cytochemical and autoradiographic investigations on normal and myelomatous plasma cells. Acta Haematol (Basel) 38:79, 1967.
Lerner RG, Parker JW: Dysglobulinemia and iron in plasma cells: ferrokinetics and electron microscopy. Arch Intern Med 121:284, 1968.
Suzuki A, Shibata A, Onodera S, et al: Histochemical study on plasma cells. Tohoku J Exp Med 97:1, 1969.
Franklin EC, Zucker-Franklin D: Current concepts on amyloid. Adv Immunol 15:249, 1972.
Bessis MC: Ultrastructure of lymphoid and plasma cells in relation to globulin and antibody formation. Lab Invest 10:1040, 1961.
Handwerger BS, Douglas SD: The cell biology of blastogenesis, in Handbook of Inflammation, edited by G. Weissman, vol 2, pp 609–706. Elsevier-North Holland, Amsterdam, 1980.
Douglas SD, Fudenberg HH: In vitro development of plasma cells from lymphocytes following pokeweed mitogen stimulation: a fine structural study. Exp Cell Res 54:277, 1969.
Fagraeus A: Antibody production in relation to the development of plasma cells. In vivo and in vitro experiments. Acta Med Scand 130:1, 1948.
Nossal CJV, Makela O: Autoradiographic studies on the immune response: I. The kinetics of plasma cell proliferation. II. DNA synthesis amongst single antibody producing cells. J Exp Med 115:209, 1962.
Sainte-Marie G: Study on plasmocytopoiesis: description of plasmocytes and of their mitoses in the mediastinal lymph nodes of ten-week-old rats. Am J Anat 114:207, 1964.
Sainte-Marie G, Coons AH: Studies on antibody production: X. Mode of formation of plasmocytes in cell transfer experiments. J Exp Med 119:742, 1964.
Parkhouse RME, Janossy G, Greaves MF: Selective stimulation of IgM synthesis in mouse B lymphocytes by pokeweed mitogen. Nature (New Biol) 235:21, 1972.
Welsh RA: Electron microscopic localization of Russell bodies in the human plasma cell. Blood 16:1307, 1960.
Shands JW, Peavy DL, Smith RT: Differential morphology of mouse spleen cells stimulated in vitro by endotoxin, phytohemagglutinin, pokeweed mitogen and staphylococcal enterotoxin B. Am J Pathol 70:1, 1973.
Andersson J, Buxbaum J, Citronbaum R, et al: IgM-producing tumors in the Balb/c mouse: a model for B-cell maturation. J Exp Med 140:742, 1974.
Weiss L: The Cells and Tissues of the Immune System: Structure, Functions, Interactions. Foundations of Immunology Series, Prentice-Hall, Englewood Cliffs, NJ, 1972.
Murphy MJ, Hay JB, Morris B, Bessis MC: An ultrastructural analysis of antibody synthesis in cells from lymph and lymph nodes. Am J Pathol 66:25, 1972.
Gobbi M, Caligaris-Cappio F, Janossy G: Normal equivalent of cells of B cell malignancies: analysis with monoclonal antibodies. Br J Haematol 54:393, 1983.
Jones NH, Clabby MI, Dialynas DP, et al: Isolation of complementary DNA clones encoding the human lymphocyte glycoprotein T1/Leu-1. Nature 323:346, 1986.
Allison A, Alt F, Arnold L, et al: A new nomenclature for B cells. Immunol Today 12:383, 1991.
Kipps TJ: The CD5 B cell. Adv Immunol 47:117, 1989.
Freedman AS, Boyd AW, Beiber FR, et al: Normal cellular counterparts of B cell chronic lymphocytic leukemia. Blood 70:418, 1987.
Defrance T, Vanbervliet B, Durand I, Banchereau J: Human interleukin 4 down-regulates the surface expression of CD5 on normal and leukemic B cells. Eur J Immunol 19:293, 1989.
Durandy A, Thuillier L, Forveille M, Fischer A: Phenotype and functional characteristics of human newborns’ B lymphocytes. J Immunol 144:60, 1990.
Caligaris-Cappio F, Gobbi M, Bofill M, Janossy G: Infrequent normal B lymphocytes express features of B-chronic lymphocytic leukemia. J Exp Med 155:623, 1982.
Casali P, Prabhakar BS, Notkins AL: Characterization of multireactive autoantibodies and identification of LEU-1+ B lymphocytes as cells making antibodies binding multiple self and exogenous molecules. Int Rev Immunol 3:17, 1988.
Hayakawa K, Hardy RR, Honda M, et al: Ly-1 B cells: functionally distinct lymphocytes that secrete IgM autoantibodies. Proc Natl Acad Sci USA 81:2494, 1984.
Stoegher ZM, Wakai M, Tse DB, et al: Production of autoantibodies by CD5-expressing B lymphocytes from patients with chronic lymphocytic leukemia. J Exp Med 169:255, 1989.
Halper J, Fu SM, Kunkel HG: Patterns of expression of human “Ia-like” antigens during the terminal stages of B cell development. J Immunol 120:1480, 1978.
Kozbor D, Moretta A, Messner HA, et al: Tp44-molecules involved in antigen-independent T-cell activation are expressed on human plasma cells. J Immunol 138:4128, 1987.
Anderson KC, Park EK, Bates MP, et al: Antigens on human plasma cells identified by monoclonal antibodies. J Immunol 130:1132, 1983.
Rebbe NF, Tong BD, Finley EM, Hickman S: Identification of nucleotide pyrophosphatase/alkaline phosphodiesterase I activity associated with the mouse plasma cell differentiation antigen PC-1. Proc Natl Acad Sci USA 88:5192, 1991.
Fithian E, Kuag P, Goldstein G, et al: Receptivity of Langerhans cells with hybridoma antibody. Proc Natl Acad Sci USA 78:2541, 1988.
Siciliano R, Pratt JC, Schmidt RE, et al: Activation of cytolytic T lymphocyte and natural killer cell function through the T11 sheep erythrocyte binding protein. Nature 317:428, 1985.
Fox DA, Hussey RE, Fitzgerald KA, et al: Activation of human thymocytes via the 50-kD T11 sheep erythrocyte binding protein induces the expression of interleukin 2 receptors on both T3+ and T3– populations. J Immunol 134:330, 1985.
Reinherz EL, Schlossman SF: The characterization and function of human immunoregulatory T lymphocyte subsets. Immunol Today 2:69, 1981.
Link M, Warnke R, Finlay J, et al: A single monoclonal antibody identifies T-cell lineage of childhood lymphoid malignancies. Blood 2:722, 1983.
Haynes BF, Martin ME, Kay HH, Kuntzborg J: Early events in human T cell ontogeny. J Exp Med 168:1061, 1988.
Chabannon C, Wood P, Torak-Storg B: Expression of CD7 normal human myeloid progenitors. J Immunol 149:2110, 1992.
Madden PJ, Littman DR, Godfrey M, et al: The isolation and nucleotide sequence of a cDNA encoding the T cell surface protein T4: a new member of the immunoglobulin gene family. Cell 42:93, 1985.
Snow PM, Terhorst C: The T8 antigen is a multimeric complex of two distinct subunits as human thymocytes but consists of homomultimeric forms on peripheral blood T lymphocytes. J Biol Chem 258:14675, 1983.
Luo K, Sefton BM: Cross linking of T cell surface molecules CD4 and CD8 stimulates phosphorylation of the Ick tyrosine phosphorylation kinase at the autophosphorylation site. Mol Cell Biol 10:5305, 1990.
Dalgleish AG, Beverley PCL, Clapham PR, et al: The CD4(T4) antigen is an essential component of the receptor for the AIDS retrovirus. Nature 312:763, 1984.
Greene WC, Leonard WJ: The human interleukin-2 receptor, in Annual Review of Immunology, edited by WE Paul, CG Fathman, H Metzger, vol 4, pp 69–96. Annual Reviews, Palo Alto, CA, 1986.
Teshigawara K, Wang HM, Kato K: Interleukin-2 high affinity receptor expression requires two distinct binding proteins. J Exp Med 165:223, 1987.
Arima N, Kamio M, Okuma M, et al: The IL-2 receptor a-chain alters the binding of IL-2 to the b-chain. J Immunol 147:3396, 1991.
Tonks NK, Charbonneau H, Diltz CD, et al: Demonstration that the leucocyte common antigen (CD45) is a protein tyrosine phosphatase. Biochemistry 27:8695, 1989.
LeFrancois L, Thomas ML, Beran MJ, Trowbridge IS: Different classes of T lymphocytes have different mRNAs for the leucocyte-common antigen T200. J Exp Med 163:1337, 1986.
Sugita K, Hirose T, Rothstein DM: CD27, a member of the nerve growth factor receptor family, is preferentially expressed on CD45RA+ CD4 T cell clones and involved in distinct immuno-regulatory functions. J Immunol 149:3208, 1992.
Janeway CA: The T cell receptor as a multicomponent signalling machine: CD4/CD8 coreceptors and CD45 in T cell activation. Annu Rev Immunol 10:645, 1992.
van Lier RA, Brouwer M, Aarden LA: Signals involved in T cell activation. T cell proliferation through the synergistic action of anti-CD28 and anti-CD2 monoclonal antibodies. Eur J Immunol 18:167, 1988.
Linsley PS, Brady W, Grosmaire L, et al: Binding of the B cell activation antigen B7 to CD28 costimulates T cell proliferation and interleukin 2 mRNA accumulation. J Exp Med 173:721, 1991.
Koulova L, Clark EA, Shu G, Dupont B: The CD28 ligand B7/BB1 provides costimulatory signal for alloactivation of CD4+ T cells. J Exp Med 173:759, 1991.
Gimmi CD, Freeman GJ, Gribben JG, et al: B-cell surface B7 provides a costimulatory signal that induces T cells to proliferate and secrete interleukin 2. Proc Natl Acad Sci USA 88:6575, 1991.
Linsley PS, Wallace PM, Johnson J, et al: Immunosuppression in vivo by a soluble form of the CTLA-4 T cell activation molecule. Science 257:792, 1992.
Kang S-M, Beverly B, Tran A-C, et al: Transactivation by AP-1 is a molecular target of T cell clonal anergy. Science 257:1134, 1992.
Timonen T, Jaksela E: Isolation of human natural killer cells by density gradient centrifugation. J Immunol Methods 36:285, 1980.
Grossi CE, Ferrarini M: Morphology and cytochemistry of human large granular lymphocytes, in NK Cells and Other Natural Effector Cells, edited by RB Herberman, p 1. Academic, New York, 1982.
West WH, Cannon GB, Kay HD, et al: Natural cytotoxic reactivity of human lymphocytes against a myeloid cell line: characterization of effector cells. J Immunol 118:355, 1977.
Lanier LL, Phillips JH, Hackett J, et al: Opinion and natural killer cells: definition of a cell type rather than a function. J Immunol 137:2735, 1986.
Hercend T, Griffin JD, Bensussan A, et al: Generation of monoclonal antibodies to a human natural killer clone: characterization of two natural killer associated antigens, NKH1a and NKH2, expressed on subsets of large granular lymphocytes. J Clin Invest 75:932, 1985.
Lanier LL, Le AM, Phillips JH, et al: Subpopulations of human natural killer cells defined by expression of the Leu7 (HNK-1) and Leu11 (NK-15) antigens. J Immunol 131:1789, 1983.
Hercend T, Schmidt RE: Characteristics and uses of natural killer cells. Immunol Today 9:292, 1988.
Steinman R: The dendritic cell system and its role in immunogenicity. Annu Rev Immunol 9:271, 1991.
Copyright © 2001 McGraw-Hill
Ernest Beutler, Marshall A. Lichtman, Barry S. Coller, Thomas J. Kipps, and Uri Seligsohn