The surface morphology of human B lymphocytes as revealed by immunoelectron microscopy

Transformation of indolent mantle cell lymphoma to pleomorphic mantle cell lymphoma: case report and review of clinical and morphologic variants

We report a case of indolent mantle cell lymphoma with progression to pleomorphic mantle cell lymphoma 8 years after initial presentation. The first lymph node biopsy showed expanded mantle zones composed of uniformly small B lymphocytes. A cyclin D1 immunohistochemical stain was negative and the patient was observed. Eight years later, the patient developed symptomatic splenomegaly. Microscopic examination of the spleen revealed expanded mantle zones with an increased number of large cells with irregular nuclear contours. Immunohistochemistry for cyclin D1 was positive. A repeat cyclin D1 immunohistochemical staining performed on the initial lymph node biopsy was positive, indicating an inadequate initial study. Immunoglobulin heavy-chain gene rearrangement studies confirmed clonal identity. A revised diagnosis of indolent mantle cell lymphoma with progression to pleomorphic mantle cell lymphoma was rendered. The differential diagnosis of mantle cell lymphoma, including clinical and morphologic variants, is discussed.

Immunoblastic lymphoma involving the bone marrow in a patient with alpha chain disease. Clinical and immunoelectron microscopic study

A patient is reported who had disseminated immunoblastic proliferation that emerged during the course of alpha chain disease. This proliferation was characterized by overt marrow invasion together with osseous and neurologic manifestations. On immunoelectron microscopic study, the malignant immunoblasts displayed varying degrees of cytoplasmic maturation and constituted a morphologic spectrum of alpha-chain-synthesizing cells, ranging from immature blasts without endoplasmic reticulum development to relatively mature plasmablasts; alpha chain was not expressed at the surface of these cells. The general features of the overt malignant stage of alpha chain disease are reviewed in reference to this unusual case. The implications of the cellular findings are discussed with regard to the maturation stage of malignant immunoblasts.

Immunohistological studies of skin biopsies from patients with lepromatous leprosy

Forty-six skin biopsies from lepromatous leprosy patients were examined for immunoglobulin and complement deposits as well as mycobacterial antigens. Rabbit anti-human immunoglobulin, rabbit anti-human C3, and rabbit anti-Mycobacterium bovis (BCG) were used as the primary antigen-detecting antibodies in a peroxidase antiperoxidase technique. Of the 26 biopsies from active erythema nodosum leprosum lesions, 6 were positive for immunoglobulin or complement deposits. These deposits were found in the dermoepidermal junction, within the foamy cells, and, in one patient, around a blood vessel. Five of twenty patients with lepromatous leprosy without erythema nodosum leprosum showed similar deposits in the dermoepidermal junction and within foamy cells. None of these patients had these deposits around blood vessels. Mycobacterial antigens were seen in all biopsies studied. The presence of acute inflammatory infiltrates did not correlate with the presence or absence of immunoglobulin or complement deposits. It is felt that immunoglobulin or complement deposits are not a constant feature of early erythema nodosum leprosum lesions and that these deposits may be secondary rather than primary in these lesions.

Hairy cell leukaemia occurring with an unrelated paraproteinaemia. A biochemical and immuno-electron microscopic study

A detailed study is described of a case of hairy cell leukaemia, presenting with a serum paraprotein of an immunoglobulin (Ig) class different from that synthesised by the neoplastic cells. The case was unusual in its association with leukaemic arthropathy but ultrastructurally the hairy cells were typical. By immunofluorenscence and immuno-electron microscopy the neoplastic cells expressed IgA lambda both on the cell surface and intracellularly in the rough endoplasmic reticulum, perinuclear space and Golgi apparatus. No Ig was observed in the ribosomal-lamellae complexes. These cells also synthesised and secreted Ig of class A lambda in culture. However the serum paraprotein was of class IgA chi and could not be attributed to an abnormal population of plasma cells in the bone marrow. There was no other evidence for myeloma and the IgA chi paraproteinaemia appeared to be benign, apparently unrelated to the neoplastic proliferation of hairy cells.

Detection of surface immunoglobulins of human lymphoid cells: a comparative study of live and fixed cells using a direct immunoperoxidase procedure

Surface immunoglobulins (Ig) of normal and malignant lymphoid cells were detected on prefixed, smeared (method A) and live (method B) cell suspensions; the results were compared with regard to staining patterns, specificity and sensitivity. In both methods surface Ig were detected by a direct immunoperoxidase procedure using conjugated purified antibody. Although method A has practical advantages, method B is more sensitive. The reasons for this discrepancy are discussed in relation to surface Ig denaturation and redistribution.

Unusual intracytoplasmic immunoglobulin inclusions in chronic lymphocytic leukaemia

Unusual intracytoplasmic immunoglobulin inclusions were found by immunofluorescence in three patients with chronic lymphocytic leukaemia. The inclusions contained the same immunoglobulin chains as those detected on the plasma membrane, except for delta chains which were expressed on the cell surface and not in the cytoplasmic inclusions. The cytoplasmic staining persisted throughout culture for 8 or more days. An initial study of patients 1's cells showed that the inclusions contained only mu chains, and kappa chains gradually became apparent after in vitro culture. In a second study, the fresh lymphocytes contained both mu and and kappa chains. Initially, biosynthetic experiments showed production of mu chains which polymerized in the cytoplasm and were not secreted. Subsequently there was synthesis of heavy and light chains which assembled into monomeric subunits that were retained and secretion of free light chains. The apparent molecular weight of these immunoglobulin chains was larger than that of their secretory counterparts. Immunoelectronmicroscopy revealed cytoplasmic mu chains in strands of endoplasmic reticulum. In the two other patients, immunofluorescence displayed unusual staining patterns of bright networks in perinuclear areas.

The lymphocyte-epithelial cell ratio in tubal mucosa of patients with cervical carcinoma

The lymphocytes in the luminal subepithelial basement membrane of the uterine tube from patients with cervical carcinoma were counted, and the results compared with those obtained from women of the same age but without cervical carcinoma (cf. Geppert et al. 1977) to determine whether a relationship exists between emigration of lymphocytes into the tubal epithelium and the clinical diagnosis of cervical carcinoma. The comparison indicated that the number of lymphocytes emigrating into the tubal epithelium during the secretory and the proliferative phase in women with cervical carcinoma is significantly lower than that in healthy women from the control group. The differences during the secretory phase were particularly pronounced. The lymphocyte count in patients with cervical carcinoma was only one third that of the healthy women in the control group. Assuming that an immunologic defect is determinative for the development of carcinoma, a decline in the number of lymphocytes emigrating into the tubal epithelium can be interpreted as the reflexion of an immunologic deficiency. It is possible that a disturbance in the lymphocytes epithelial cell ratio in this stage of life could indicate a disposition for those tumors the incidence of which is high in this age group (e.g., squamous cell carcinoma of the cervix). Further study is necessary to establish whether these cells be classified as B or T lymphocytes.

The contribution of scanning electron microscopy in haematology: its role in defining leucocyte and erythrocyte disorders

This report reviews the contribution of scanning electron microscopy (SEM) in haematology. Important observations regarding red cell shape and deformities are referred to and contributions in the definition and classification erythrocyte disorders are stressed. In this field there is no doubt that SEM has contributed much to the three-dimensional visualization of RBC disorders. As far as leucocyte pathology is concerned the situation is less clear. SEM has contributed much to current knowledge and understanding of the surface properties of white blood cells. Normal leucocytes have different surface features and can be distinguished under the SEM. However, some overlap does occur, making individual distinction on the basis of surface architecture alone extremely difficult. The difficulties in this regard are discussed in this review and factors influencing the variability of surface microprojections are reviewed briefly. Leukaemic cells of different origins may also be distinguished under the SEM. However, while "hairy' cells have typical surface features and non-lymphoid leukaemic cells, in particular monocytes, are readily distinguished from lymphoid leukaemic cells, there is much overlap of surface topography. Undifferentiated cells and early myeloblasts and lymphoblasts have similar surface features and cannot be distinguished under the SEM. While SEM adds a valuable third dimension to morphology and ultrastructure, it cannot be used alone in the definition of difficult cases of acute leukaemia.

Positive identification of human leukaemic cells with scanning immuno-electron microscopy, using antibody coated polystyrene (latex) beads as markers

Scanning immuno-electron microscopic labelling techniques were successfully used to identify a variety of leukaemia-lymphoma cells. Anti-T, -B and -common type acute lymphoblastic leukaemia (ALL) antisera were covalently conjugated to polystyrene latex spheres by means of glutaraldehyde. Peripheral blood mononuclear cells obtained from healthy individuals and from patients with T-type ALL, B-type chronic lymphocytic leukaemia (CLL), acute and chronic non-lymphoblastic leukaemias (ANLL) and cultured leukaemia-lymphoma cells were incubated with the above antisera-latex conjugates. Positively labelled cells were easily identified by the presence of latex spheres on their surfaces. Cross reactivity of the antisera used and non-specific attachment of the markers were infrequently encountered. The results of this study confirm earlier scanning electron microscopic reports indicating that different leukaemic cells have characteristic surface features and show that scanning immuno-electron microscopy (SIEM) can readily be applied to the study of human leukaemic cells.

Ultrastructural studies of peripheral blood lymphocytes in T cell-depleted rabbits. A scanning and transmission electron microscopic analysis

Density separation of purified peripheral blood leucocytes from T-cell depleted rabbits on a linear Ficoll-metrizoate gradient has been applied to obtain different leucocyte fractions. Two lymphocyte fractions separated on density seem to have different characteristics, both morphologically and immunologically. In this study these two fractions have been characterized ultrastructurally by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and a relationship has been established between the surface architecture (SEM), the cell size (SEM/TEM) and surface-Ig/C3-receptors (LM, light microscopy). Finally three types of lymphocytes have been described in the two lymphocyte fractions separated on density. Morphometric information such as cell size, cell shape, eu-/heterochromatin ratio in the nucleus and the nucleus-/cell ratio have been correlated to the stage of activation of the B lymphocyte in a representative density separation.

Age-related morphological changes in lymphocytes as a model of aging

The same age-related morphological changes have been observed in the lymph node and spleen lymphocytes of old untreated Wistar rats and CBA/Ca mice. The same age-related changes were also observed in the peripheral lymphocytes of healthy humans. The most important changes were seen in the mitochondria of the lymphoid cells. They were sometimes swollen; the mitochondrial cristae disappeared and were replaced by myelin-like forms or filamentous structures. The mitochondrial changes developed only in non-labelled lymphoid cells, presumably the T cells. It is suggested that lymphocytes be used as a morphological model for the study of aging and its modification.

The intracellular localisation of immunoglobulin in human lymphoid cells and haematopoietic cell lines by immunoperoxidase electron microscopy

A technique is described for the ultrastructural localisation of intracellular immunoglobulin (Ig) in human lymphoid cell suspensions by the immunoperoxidase method. The technique involves restricted saponin digestion of glutaraldehyde prefixed cells to enhance conjugate penetration. With this method of staining Ig was located in the rough endoplasmic reticulum, perinuclear space and Golgi apparatus in human lymphoid cells from a variety of sources, which is consistent with previously published observations using other ultrastructural techniques. In contrast, diffuse intracytoplasmic staining was predominant in cells prefixed with glutaraldehyde but not treated with saponin. These differences in patterns are discussed in terms of membrane permeability. Although saponin treatment was necessary for consistent localisation of intracellular Ig it resulted in unavoidable loss of Ig from the surface of the cells.

The distribution of HLA on human lymphoid, bone marrow and peripheral blood cells

The cellular distribution and the differential expression of HLA on cell suspensions and tissue sections has been investigated using the monoclonal antibody W6-32, which reacts with the high molecular weight chain of the major histocompatibility antigen. Lymphocytes and platelets, as assessed by autoradiographic and immunoperoxidase labeling, were the most densely labeled cells. Myeloid precursors showed more labeling than mature neutrophils. Electron microscopic immunoperoxidase labeling showed a continuous distribution of HLA antigen on lymphoid and myeloid cell membranes. Erythroid precursors (including reticulocytes), although very weakly labeled, were clearly positive, in comparison with mature erythrocytes. In the thymus, HLA-negative, thymocyte antigen-positive cells (85%) can be distinguished from HLA-positive, thymocyte antigen-negative cells (15%). By using immunofluorescence techniques on tissue sections, the former cells were shown to be cortical thymocytes and the latter medullary cells.

Purine nucleoside phosphorylase in lymphocytes of various mammalian species

The distribution of purine nucleoside phosphorylase has been assessed by light and electron microscopy in peripheral lymphocytes of man, the rabbit, rat, mouse, guinea-pig, pig and dog. The enzyme activity was detected in the cytosol of the majority of lymphocytes in all species. The amount of reaction product was high in the rabbit, man, guinea-pig and dog, mpderate in the rat and very low in the pig and mouse. Other blood cell types are reactive as well, although there is a variation between species. A possible relationship of purine nucleoside phosphorylase with particular subpopulations of lymphocytes is suggested.

Surface morphology of bone marrow lymphocytes. I. Scanning electron microscopy of small lymphocytes bone marrow and spleen

Cell separation techniques and scanning electron microscopy (SEM) were used to characterize the surface morphology of small lymphocytes in mouse bone marrow. Lymphocyte-rich fractions and unfractionated suspensions of bone marrow and spleen cells from 9--10-week-old C3H male mice were glutaraldehyde-fixed, syringed onto gelatin-coated silver membranes, dehydrated in ethanol, infiltrated with amyl acetate, critical point dried, coated with gold-palladium and examined by SEM. High proportions of cells were retained on the membranes. Purified spleen small lymphocytes showed unimodal distribution curves for cell diameter (mode, 3.4 micrometer) and for number of surface microvilli (mode, 55--60). Bone marrow small lymphocytes were identified initially in lymphocyte-rich marrow fractions and in erythroblast-depleted marrow from polycythemic mice as well as in normal whole marrow. The cells resembled spleen small lymphocytes in size distribution and they showed microvilli. However, the number of visible microvilli was lower on small lymphocytes in the bone marrow (mode, 35--40) than in the spleen. While in each small lymphocyte population the total number of microvilli was greater on larger cells than on smaller ones, the density of microvilli per unit area of cell surface tended to decrease with increasing cell size. The results establish that the small lymphocytes in mouse bone marrow, mainly locally-produced immature cells, have villous surfaces, but the number of microvilli per unit cell surface area is less than that on peripheral small lymphocytes, as seen in the spleen. Neither in the bone marrow nor in the spleen are subpopulations of small lymphocytes distinguishable solely by numbers of microvilli. The findings suggest that microvilli on bone marrow small lymphocytes may undergo further development during post-mitotic maturation, surface receptor expression and migration of the cells to peripheral lymphoid tissues.

Murine macrophage-lymphocyte interactions: scanning electron microscopic study

Light and scanning electron microscopic observations revealed murine macrophage-lymphocyte interactions involving the initial contact of peritoneal, spleen, or thymus lymphocytes with peritoneal macrophage processes or microprocesses followed by clustering of lymphocytes over the central nuclear area of the macrophages. Lymphocyte-lymphocyte clustering was not observed in the absence of macrophages. Attachment and subsequent clustering appeared not to require the presence of serum or antigen; the attachment of allogeneic or xenogeneic lymphocytes was comparable to that seen in the syngeneic system, but central clustering of these lymphocytes failed to occur. No attachment or clustering was observed when thymic lymphocytes were cultured with thymus derived fibroblasts rather than with peritoneal macrophages. Lymphocyte attachment to immune, antigen-activated, syngeneic macrophages occurred more rapidly than that to normal unstimulated syngeneic macrophages; however, lymphocytes attached to the "activated" macrophages appeared to be killed by a nonphagocytic mechanism. A similar increase in the rate of lymphocyte attachment to macrophages occurred in the presence of migration inhibitory factor. Subsequent lymphocyte clustering on macrophages was observed in the migration inhibitory factor-stimulated cultures. In addition, lymphocyte-macrophage interactions similar to those in vitro were observed to occur in vivo on intraperitoneally implanted cover slips.

Uranyl-labelled antibody (ULA) method and its application for Rh antibodies

The existent labelling materials for studies of antigen--antibody interaction at ultrastructural level, namely ferritin and peroxidase, because of their large molecular size do not fulfill all requirements of excellent markers for electron microscopy (EM). Uranyl acetate has a molecule 354 times smaller than IgG and its uranium atom is electron-dense. These physical characteristics of uranyl acetate make it a labelling material par excellence as described in this article. Quantitative and qualitative studies of Rh antigen-antibody interactions are for the first time presented at the ultrastructural level, and the application of the uranyl-labelled antibody (ULA) method for weak antisera (dilutions 100 to 1000 time higher than the Coombs range of sensitivity) is demonstrated. The ULA method opens a new era for studies of antigens, antibodies and their interactions because it will demonstrate visibly details of the antigen-antibody interaction and is especially suitable for studies of weak antisera.

The detection of membrane and cytoplasmic immunoglobulins in human leucocytes by immunoperoxidase staining

A sensitive immunoperoxidase technique for the detection of immunoglobulin (the peroxidase--anti-peroxidase or PAP procedure) has been applied to fixed smears of normal human white cells. IgM was detected in approximately 5% of lymphocytes from normal donors. Most positive cells showed a characteristic 'hairy' peripheral staining pattern; a similar morphological appearance was seen in samples stained for IgD. The membrane (rather than cytoplasmic) localization of this IgM was inferred from the redistribution of staining induced by preliminary incubation of cell suspensions with anti-mu antisera before smearing and staining. B cell-depleted and B cell-enriched suspensions showed, respectively, reduced and increased percentages of IgM-positive cells. IgG was detectable in approximately 25% of normal lymphoid cells. In contrast to the IgM and IgD reaction patterns, these cells commonly showed a discontinuous distribution of reactivity, often localized to the cell uropod or to small cytoplasmic vesicles. However, when cells were prepared at 0 degree C, staining tended to be diffuse. These findings suggested that the PAP procedure was detecting Fc receptor-bearing lymphoid cells which had bound serum IgG. IgG was also demonstrated in normal polymorphs and monocytes. The specificity of this reaction was confirmed by the use of immunoabsorbant-purified antibodies. The possible practical advantages of this immunoperoxidase procedure for the detection of leucocyte immunoglobulin are considered, and the relevance of the demonstration of IgG in non-lymphoid cells to recent reports of this immunoglobulin in Hodgkin's disease and malignant 'reticulum' cells is briefly discussed.

A scanning electron microscopic and immunologic study of B-cell lymphosarcoma cells in cerebrospinal fluid

Homogenous populations of malignant cells from the spinal fluids of two patients with metastatic lymphosarcoma were studied immunologically and by scanning electron microscopy (SEM). The malignant cells in both spinal fluids were shown to be of B-cell origin. The surface morphology of these cells was variable with the majority of the cells having numerous microvilli and a minority having few or no microvilli. This appears to be the first report on the surface ultrastructure of B-lymphosarcoma cells suspended in spinal fluid.

Scanning electron microscopic investigations of acute leukemia

Twenty cases of acute lymphoblastic leukemia (ALL) in children and adults were investigated at different tissue localizations by scanning electron microscopy. ALL was divided into cases with or without strong paranuclear acid phosphatase activity. ALL showed very similar surface morphology irrespective of the type of ALL or the tissue localization. ALL is, however, strikingly different in some from other childhood leukemias and lymphomas, as well as from activated T-lymphocytes in infectious mononucleosis. The results indicate that the surface morphology of leukemic cells is a stable cytologic parameter, if certain technical prerequisits are fulfilled. Further criteria may thus be added to the panel of known cytologic, cytochemical and functional parameters.

Surface features of Sezary cells: A scanning electron microscopy study of 5 cases

The surface features of circulating cells from 5 patients with typical Sezary's Syndrome (SS) are described using scanning electron microscopy (SEM). Sezary cells prepared by different methods, with and without prior fixation in cell suspension, showed similar surface architectures. SS cells were mostly spherical and moderate to markedly villous in appearance, and in this respect, resembled the majority of circulating lymphocytes from patients with chronic lymphocytic leukaemia (CLL). A proportion of cells were larger and more irregular in shape while others had small extensions of cytoplasm resembling small uropods with clusters of polarised microvilli. Despite the latter findings, most SS cells cannot be distinguished from CLL cells on the basis of their surface architecture under the SEM.

The cellular distribution of erythrocyte and normoblast A1 and A antigens in normal and preleukemic states. An immunoelectron microscopy study

A1 and A alloantigens were visualized on human erythrocytes and normoblasts by immunoelectron microscopy using peroxidase-coupled antibodies. Specimens were obtained from patients with preleukemia and associated antigen weakening, and from individuals with normal antigen values. Cells were fixed by glutaraldehyde and subsequently reacted with antibodies.

The heterogeneity of erythrocyte antigen distribution in human normal phenotypes: an immunoelectron microscopy study

A and A1 antigen were detected on human blood erythrocytes by immunoelectron microscopy using peroxidase-conjugated antibodies. Cells were obtained from various normal A subgroups, including rare weak A phenotypes and infant (cord blood) samples. Erythrocytes were fixed prior to incubation with specific reagents. The detection of surface antigens was carried out by an indirect method involving anti-A and anti-A1 antibodies and conjugated anti-immunoglobulin antibodies. The surface labelling was seen as a diffuse dense layer. Haemperoxidase-like activity resulted in a faint background which did not interfere at the level of ultrathin sections, with surface staining due to exogeneous peroxidase. The most significant finding was the existence, in a given sample, of several populations of cells as revealed by their antibody-binding capacity. The distribution of the various populations varied from one sample to another according to its subgroup. The progressive weakening of phenotype expression which characterizes the various subgroups from A1 to A weak was paralleled by a decreasing number of "antigen rich" cells, which were still detectable in weak phenotypes as a minor population. This study confirms that a given normal phenotype in fact represents a mixture of antigenically different populations of erythrocytes.

Acute lymphoblastic leukemia: a study of 25 cases by scanning electron microscopy

Cells from 25 cases of acute lymphoblastic leukemia (ALL) were studied under the scanning electron microscope (SEM). In 24 of the cases, the vast majority of circulating leukaemic cells had few microvilli. Villous cells were rarely encountered and prominent ridge-like profiles and ruffled membranes were not seen. Only six cases were studied by immunological techniques and four of the cases were of the null type while in two the cells bore detectable T-markers. It seems that ALL is almost always associated with the presence of cells with few microvilli in the peripheral circulation, differing in this respect from most cases of CLL. Although circulating leukaemic lymphocytes with few microvilli are sometimes seen in CLL, the most frequent cell type encountered is a more villous lymphocyte. Differences between leukaemic cells from patients with ALL, CLL and non-lymphoblastic leukaemias are discussed. It appears that SEM may help to distinguish lymphoblastic and nonlymphoblastic leukaemic cells in many instances and can be used as a useful adjunct to other modes of microscopy in the diagnosis of acute leukaemia.

Immune complex receptors on cell surfaces. II. Cytochemical evaluation of their abundance on different immune cells: distribution, uptake, and regeneration

A recently developed method for ultrastructural demonstration of cell surface receptors for immune complexes is applied to evaluation of these receptors on various cell types. The method entailing incubation with a complex of horesradish peroxidase (HRP) and antibody to HRP (anti-HRP) disclosed dense foci indicative of immune complex receptors distributed at 30- to 120-mmu intervals over macrophage surfaces. Invaginations, loop-like evaginations, and pinocytotic vasicles stained prominently. The number of stained immune complex receptors averaged 200,000 per oil-induced macrophage and 120,000 per noninduced macrophage, as determined from counts of focal deposits in electron micrographs. Receptor periodicity on giant cells present in oil-induced exudates resembled that on macrophages, but the larger giant cells contained an estimated 1.5 million sites. Although receptor periodicity on eosinophils and neutrophils equaled that on macrophages, the staining was lighter and was interrupted by intervals of unstained membrane. Neutrophils averaged 28,000 and eosinophils 35,000 receptors per cell, whereas those lymphocytes with receptors averaged 3,500 per cell. Viable cells incubated with anti-HRP sequentially exhibited about half as many reactive sites as did cells incubated with immune complex. When warmed to 37 C, viable macrophages and eosinophils pinocytosed soluble immune complexes almost completely within 30 minutes and phagocytosed insoluble complexes more slowly. The endocytosed soluble immune complexes were sequestered within tubulovesicular structures in addition to the expected phagocytic vacuoles. Receptors appeared fully active on macrophages that were restained with soluble, cold immune complex after they had endocytosed immune complex in the course of a 30-minute warming interval.

[Electronmicroscopic and immunohistochemical studies on human lymphocytes]

Lymphocytes from the blood of healthy individuals and of patients suffering from CLL were investigated by electron microscopy and peroxidase-immunohistochemistry. B-lymphocytes were labelled by heterologous, peroxidase-conjugated antisera directed against the Id-determinants of their membranes. T-lymphocytes were labelled by an indirect method: specific incubation with a specific anti-T-cell-globulin from the rabbit; labelling-incubation with a peroxidase-conjugated anti-rabbit-IgG-globulin from the sheep. In addition, T-lymphocytes were identified by their ability to form rosettes with sheep erythrocytes spontaneously. The quantitative results were: about 80% T-lymphocytes and about 24% B-lymphocytes in normal persons, the opposite results in CLL. T- and B-lymphocytes were photographed electron microscopically; the number of organelles in the single cells was evaluated: lysosomes in the average are more numerous in T-lymphocytes, ergastoplasm in B-lymphocytes, mitochondria are equally distributed in both groups of cells. There is so much overlapping, however, that the single cell only with the aid of immunochemistry or rosette formation can be identified as a B- or T-cell. In both, the T- and the B-cell-series, different forms of lymphocytes can be distinguished according to the degree of cell differentiation. Some further problems, as specificity of the antisera and labelling of the cells by means of their Fc-receptor are discussed.

Surface features of cells in human lymphoproliferative disorders. An immunoelectron microscopy study

Peroxidase conjugated antibodies were applied to cell suspensions in order to detect surface associated immunoglobulins. Cell suspensions were fixed prior to incubation with reagents, a procedure avoiding membrane alterations induced by antibodies to surface component. By immunoelectron microscopy an identification of B lymphocytes could be made with simultaneous observation of their surface architecture. Basic findings were that normal circulating human B lymphocytes had a villous surface. This relationship was not confirmed however by examinating samples from various B and T cell proliferations establishing that surface morphology is not sufficient to categorize cells in disease. Specimens from hairy cell leukemia were also examined. Despite salient surface characteristics as revealed by the present method, the categorization of cells remains unclear.

A scanning electron microscopy and immunological study of 84 cases of lymphocytic leukaemia and related lymphoproliferative disorders

The surface features of cells from 84 cases of lymphocytic leukaemia, and related lymphoproliferative disorders are described as seen by scanning electron microscopy (SEM). Most of the 46 cases of CLL were shown to be B-derived, but rare cases of mixed B and T cell leukaemia and leukaemia with cells bearing both B and T markers were also encountered. Despite the existence of a spectrum of cell surface morphology, it was possible in many cases to identify a dominant cell type. Cells from cases of B derived malignancies were most frequently of the 'predominantly villous' type while a smaller proportion of cases were of the predominantly 'smoother' or 'mixed villous and smooth' type. Variations in surface morphology also occurred with progression of the disease. In most cases of acute lymphoblastic leukaemia (ALL) 'smoother' cells predominated. However, more cases of ALL and T derived leukaemia need to be examined before definite conclusions can be drawn concerning the surface of these cell types. This study also illustrates the importance of examining large numbers of cases of leukaemia, before conclusions are drawn concerning their surface features and indicates that SEM cannot consistently distinguish between leukaemic B and T cells. It will be of interest to determine whether the surface architecture of the leukaemic cell is related to the degree of cell differentiation and eventual prognosis in these cases.