Leu 7+(HNK-l+) Cells

In the present study, combined methods (indirect immunofluorescence with monoclonal antibodies, Percoll density fractionation, FACS analysis, and the cytotoxicity test) were used for further characterization of peripheral blood Leu 7+ cells (human NK and K cells). The Leu 7+ cell content was found to be relatively higher in the low-density cell fraction in which cells of large granular lymphocyte morphology predominated. However, Leu 7+ cells were also present in intermediate and high-density fractions. Low-density Leu 7+ cells were characterized by both Leu 2 (T suppressor/cytotoxic) and OKM1 (myelomonocytic) markers, whereas among high-density Leu 7+ cells the Leu 2 phenotype strictly predominated. Depletion of OKT3+ cells from the non-adherent cell population caused a decrease of cells with T helper and T suppressor phenotypes but did not have this effect on Leu 7+ and OKM1+ cells. After depletion of Leu 7+ cells from the OKT3- population the content of both T suppressor and OKM1+ cells decreased. Both the present results and previous reports enable us to conclude that two main Leu 7+ cell subpopulations are present in blood, namely Leu 7+Leu 2+/Leu 4+ and Leu 7+/OKM1+ cells. The presence of small and large Leu 7+ cells was also shown by FACS analysis.     

Histiocytic sarcoma (true histiocytic lymphoma): a clinicopathological study of 20 cases

Large-cell non-Hodgkin's lymphomas (T- and B-immunoblastic, centroblastic and true histiocytic lymphomas) have a heterogeneous clinical course. In the present study the clinical and morphological data of 20 cases of histiocytic sarcoma (true histiocytic lymphoma) are presented. Diagnosis was supported by immunohistochemistry, cytochemistry, rosette assays and/or electron microscopy. Although the follow-up was relatively short (up to 144 months, mean 26 months), the clinical data differed clearly from the series of large-cell non-Hodgkin lymphomas, recorded in the literature. Differences were found in age distribution with a peak in the third decade, in organ involvement showing a preference for skin, gastrointestinal tract and bone, and in response to therapy. In general, histiocytic sarcoma appears to have a more favourable response to therapy and clinical course than the other large-cell lymphomas (T- and B-immunoblastic and centroblastic lymphomas). Moreover, preliminary observations in the group of histiocytic sarcomas suggested that the presence of lysozyme and/or 5-nucleotidase and the absence of alpha 1-antitrypsin in the cytoplasm is associated with a better response to therapy and favourable clinical course.     

Monoclonal antibody analysis of T-lymphocyte subsets in young and aged adults

Eleven monoclonal antibodies identifying surface antigens present on human T lymphocytes were utilized to investigate the effects of advanced age on peripheral blood lymphocyte subsets. Both the proportion and number of lymphocytes recognized by five antibodies reactive with 'pan' T cell antigens (OKT3, OKT11, Leu4, T101 and Lyt3) decreased with age. The percentage of helper/inducer (OKT4+, Leu3a+) cells remained constant; however the proportion of Leu2a+, suppressor/cytotoxic cells declined. There was no change with age in the percent representation of OKT9+ or OKT10+ cells, nor in the ratio of helper/inducer to suppressor/cytotoxic cells (OKT4+/OKT8+ or Leu3a+/Leu2a+). Absolute numbers of helper/inducer (OKT4+, Leu3a+), suppressor/cytotoxic (OKT8+, Leu2a+), OKT9+ and OKT10+ cells were lower in elderly individuals as the result of lymphocytes constituting a lower percentage of the peripheral blood white cell population in this age group. While only small differences existed between the lymphocyte populations of young and aged men; aged women, compared to young women, had more dramatic shifts in their T cell populations. Comparison of antibodies putatively identifying similar (the same) functional groups of T cells demonstrated excellent correlation between the percentage of cells enumerated with the antibodies OKT3+: Leu4+ (r = .951), OKT4+: Leu3a+ (r = .914), OKT8+: Leu2a+ (r = .896), and in the ratio of helper/inducer to cytotoxic/suppressor OKT4+/OKT8+: Leu3a+/Leu2a+ (r = .926) cells.     

The cellular composition of granulomas in mesenteric lymph nodes from patients with Crohn's disease

Summary The immunohistochemical findings in granulomatous lymphadenitis in patients with Crohn's disease are presented and compared with conventional light microscopic findings. The cellular composition of the granulomas in mesenteric lymph nodes was examined with a broad panel of monoclonal and polyclonal antibodies directed to B-cells, T-cells, monocytes/macrophages, dendritic reticulum cells, HLA-DR antigens and the transferrin receptor. The centre of the granulomas contains OKIa⁺, OKM1⁺, OKT9⁺, DRC^–, To5^– epithelioid cells and giant cells and OKT3⁺ lymphocytes. In general, the majority of the small lymphocytes within the granulomas expresses the OKT3⁺, OKT4⁺ Leu 3a⁺ phenotype which points toward T-helper cells. Fewer OKT3⁺ OKT8⁺ T suppressor/cytotoxic cells are observed. At the periphery of the granulomas a lymphocytic corona composed of BA1⁺, B1⁺ B lymphocytes may be present.From these findings it can be concluded that the granulomas in mesenteric lymph nodes from patients with Crohn's disease are composed of centrally located T-lymphocytes and of epithelioid cells which are of monocyte/macrophage origin and have the characteristics of antigen-presenting cells.     

Reactivity of Leu 1 and T101 monoclonal antibodies with B cell lymphomas (correlations with other immunological markers)

The reactivity of Leu 1/T101 monoclonal antibodies (MoAb) was studied in a series of 69 lymphomas with B cell differentiation and was correlated with other cell markers. A three step immunoperoxidase technique on frozen sections was used to test a panel of 20 MoAb: anti-human Ig (heavy and light chains), To 15 (Pan B cells), Leu 1, T101, Leu 4, Leu 3a, Leu 5, OKT 8, OKT 6, Leu 7, anti-CALLA (IOT 5), Leu 10, anti-HLA-DR, OKM 1 and anti-dendritic reticulum cells (R 4/23). T101/Leu 1 antigen was detected in 24 cases: CLL (11 of 11), diffuse centrocytic lymphomas (four of 11), follicular lymphomas (none of 12), follicular and diffuse lymphomas (seven of 10) and one unclassified low grade lymphoma. This antigen was observed in only one high grade malignant lymphoma. In follicular lymphomas, two results deserve attention: (1) T101+ lymphomas showed most frequently IgM+, IgD+ surface Ig. Inversely, T101 unreactive lymphomas displayed IgM+, IgD+ phenotype. (2) Tp67 antigen (T101, Leu 1) and CALLA (GP 100) were found to be mutually exclusive in these lymphomas. These results suggest that follicular lymphomas could be derived from two distinct germinal center cell populations: IgM+ Ig'D-, Calla+, Leu 1-/T101- and IgM+, IgD+, CALLA-, Leu+/T101+.     

The immunologic and ultrastructural characterization of the cellular infiltrate in acute cardiac allograft rejection: prevalence of cells with the natural killer (NK) phenotype

The inflammatory cell infiltrates in 15 endomyocardial biopsies serially obtained from a human cardiac allograft during a 1 1/2-year period were characterized. An indirect immunofluorescent technique with hybridoma-derived monoclonal antibodies which preferentially react with B lymphocytes (anti-Ia), mature T cells (OKT3, Leu 1), and helper (OKT4b,d) and supressor/cytotoxic (OKT8) T-cell subsets and with natural killer cells, macrophages, and granulocytes (OKM1) was used. During each of seven rejection episodes the overwhelming majority of infiltrating cells in the endomyocardial biopsy were OKM1+Ia. These cells displayed short microvilli, a moderate amount of cytoplasm, numerous mitochondria, a large amount of rough endoplasmic reticulum, Golgi, and an indented nucleus, that is, the ultrastructural features of large, granular lymphocytes. Thus, they morphologically and phenotypically resemble those lymphoid cells which have been shown to possess natural killer (NK) functions in man. Occasional Leu 1+OKT3+ cells, some of which were OKT8+, were also seen during acute rejection. In each instance following therapy and resolution of the rejection episode only rare OKM1+Ia- cells were present. At this time the majority of the cells were Leu 1+OKT3+OKT8+. Routine biopsies, performed at times without evidence of rejection, showed only reactivity for Ia antigens by the capillary endothelium. These studies demonstrate the prevalence of cells with the natural killer phenotype in this human cardiac allograft during episodes of acute graft rejection.     

Cellular composition of suppurative granulomas: an immunohistochemical study of suppurative granulomatous lymphadenitis

The immunohistochemical findings from an investigation of suppurative granulomatous lymphadenitis (SGL) are presented. With a broad panel of monoclonal and polyclonal antibodies directed against B cells, T cells, monocytes/macrophages, HLA-DR antigens, and the transferrin receptor, early, nonsuppurative granulomas were found to consist of OKM1+ OKIa1+ OKT9+ epithelioid histiocytes and multinucleated giant cells, admixed with variable numbers of OKT4+ Leu-3a+ helper/inducer T cells. These nonsuppurative lesions were surrounded by distinctive cuffs of BA1+ B1+ sIgM+ sIgD+ OKIa1+ lymphocytes. In contrast, suppurative granulomas were bordered by palisades of OKM1+ OKIa1+ OKT9+ epithelioid histiocytes, admixed with some OKT8+ suppressor/cytotoxic T cells. These suppurative lesions lacked distinctive cuffs of B lymphocytes, but half of the lesions were surrounded by numerous plasma cells that expressed cytoplasmic IgA and IgG. Based on these immunohistochemical findings, it is concluded that a shift in the nature of the predominant intragranulomatous T-cell subset occurs during the successive phases of the immune response in SGL. The cause of the central necrosis and suppuration may be related to the excessive numbers of intragranulomatous OKT8+ T cells or to the formation of immune complexes by the surrounding plasma cells.     

Hepatic vascular endothelial cells heterogenously express surface antigens associated with monocytes,macrophages and T lymphocytes

Summary During studies of the antigenic and functional properties of hepatic sinusoidal lining cells in situ, we found that only the sinusoidal endothelial cells share antigens with a peripheral blood macrophage subset capable of presenting soluble antigens and triggering autologous mixed lymphocyte reactions. They were HLA-DR+, OKM1–, OKM5+. Vascular endothelial cells in the portal areas and central veins were HLA-DR+, OKM1– and OKM5–. The sinusoidal endothelial cells also expressed an antigen found on helper/inducer (OKT4 and Leu3 a) T lymphocytes. Thus, the present study suggests that endothelial cells in different anatomic compartments in the liver heterogenously express surface antigens associated with monocytes, macrophages and T lymphocytes and possess distinct immunological functions.     

Interstitial nephritis related to nonsteroidal anti-inflammatory agents and beta-lactam antibiotics: a comparative study of the interstitial infiltrates using monoclonal antibodies

Acute interstitial nephritis (AIN) is a common pattern of renal injury induced by therapeutic agents. In order to characterize the types of mononuclear leukocytes infiltrating the kidney in drug-induced interstitial nephritis, a panel of monoclonal antibodies (Leu1, Leu3a, OKT8, OKM1, Leu14, OKT17, IL-2) was applied to cryostat sections of 13 renal biopsies (five non-steroidal anti-inflammatory agents (NSAID) (Group I); five beta-lactam antibiotics (Group II), 3 miscellaneous (Group III]. The majority of infiltrating mononuclear leukocytes were Leu1-positive T cells (71.7 +/- 18.7%), followed by monocytes (15.2 +/- 7.7%) and B cells (7.4 +/- 9.1%). Leu3a/OKT8 ratio was 0.954 +/- 0.341. Rare cells reacted with antibody to the interleukin-2 receptor (1.4 +/- 1.2%). No statistically significant differences could be found in the percentages of T lymphocytes, B lymphocytes, monocytes, activated (IL-2+) T cells or Leu3a/OKT8 (helper/suppressor) ratios in the three groups. In Group II, the following pathologic correlations were seen: Leu3a/OKT8 versus interstitial inflammation (R = -0.848), percent Leu3a versus interstitial inflammation (R = -0.818), percent OKT17 versus tubulitis (R = 0.785), percent Leu14 versus tubular atrophy (R = -0.891), and interstitial edema (R = 0.965). Our findings support a role for cellular immune mechanisms in the pathogenesis of AIN related to both NSAIDs and beta-lactam antibiotics.     

Morphometric characterization of diffuse large-cell (histiocytic) lymphomas.

From 28 large-cell lymphomas, defined by marker studies, enzyme histochemistry, and electron microscopy as large noncleaved follicle center cell tumors (lnc FCC), B-immunoblastic or true histiocytic lymphomas, morphometric cell parameters, including nuclear size and shape, cytoplasmic area, and cytoplasm-to-nucleus ratio, were measured. Moreover, size, number, and location of nucleoli in the nuclei of the characteristic cells of lnc FCC and B-immunoblastic lymphoma were determined. Statistical evaluation of the data showed the nuclear shape to be the most sensitive parameter in the differentiation of true histiocytic lymphoma from lnc FCC and B-immunoblastic lymphomas. With nucleolar parameters lnc FCC could be differentiated from B-immunoblastic lymphoma: lnc FCC had a higher mean number of nucleoli per cross-section of nucleus and more eccentrically located nucleoli. Moreover, the measurements show that the differences in number and location of nucleoli between large noncleaved follicle center cells and B-immunoblasts are smaller than generally described in the literature. Our results show that it is possible to differentiate by morphometry between lnc FCC, B-immunoblastic, and true histiocytic lymphomas.     

Morphologic and immunologic characterization of 50 peripheral T-cell lymphomas.

Fifty T-cell lymphomas, excluding mycosis fungoides and lymphoblastic lymphoma, were studied morphologically and immunohistochemically with a panel of monoclonal antibodies reactive with T-cell differentiation antigens in fresh frozen tissue. Histologically, 36% of the lymphomas were large-cell immunoblastic, 26% were diffuse large-cell, 22% were diffuse mixed small and large-cell, and 16% were monomorphic medium-sized-cell lymphomas. By immunologic studies, 64% of the lymphomas were of helper phenotype, 12% were of cytotoxic/suppressor phenotype, 8% expressed both helper and cytotoxic/suppressor suppressor antigenic markers, and 16% lacked detectable markers for either helper or cytotoxic/suppressor cells. There was no correlation between histologic category and immunophenotype. A common finding, and one which may prove to be helpful in the diagnosis of T-cell lymphomas, was the loss of one or more of the pan-T antigens Leu 1, 4, and 5 or the T-cell antigen Leu 9 in 32 cases. The expression of Leu 1 and Leu 9 was lost in 46% of cases, expression of Leu 4 was lost in 26%, and expression of Leu 5 was lost in 24%. About three-quarters of the lymphomas expressed Ia antigens.     

Lupus lymphadenitis: report of a case with immunohistologic studies on frozen sections

A case of lupus lymphadenitis with frozen section immunohistologic studies is presented. Clinically, the patient had well-documented systemic lupus erythematosus (SLE) when rapid development of generalized lymphadenopathy raised the possibility of a diagnosis of malignant lymphoma. Histologically, the findings of paracortical foci of necrosis and hematoxylin bodies were diagnostic of SLE. Granulocytes were absent. Monoclonal antibodies applied to frozen sections demonstrated two predominant cell populations within and surrounding the paracortical zones of necrosis: OKM1+, Leu-M1+ histiocytes and OKT8+, Leu-4+ T cytotoxic/suppressor cells. In the lymph node not involved by necrosis, lymphoid follicles were composed of polytypic B cells and the interfollicular regions of T cells. Leu-3a+, Leu-4+ T helper/inducer cells outnumbered T cytotoxic/suppressor cells in a 3:1 ratio. Since lupus lymphadenitis may closely resemble histiocytic necrotizing lymphadenitis of Kikuchi and Fujimoto, particularly if hematoxylin bodies are not found, we compared the findings in this case with findings of cases of histiocytic necrotizing lymphadenitis of Kikuchi and Fujimoto reported in the literature. The immunologic findings in both diseases are similar. We conclude that immunologic studies using frozen sections are probably of no help in differentiating between these two disorders when histologic findings are not conclusive.     

Leu 7+(HNK-l+) Cells

In the present immunohistochemical studies, Leu 7+ (HNK-1+, human natural killer and killer) cells were found to occupy preferentially germinal centres of follicles in lymph nodes and tonsils. Leu 7+ cells were also present in germinal-like zones of spleen follicles and in mantle zones of hyperplastic thymus follicles and varied in localization in lymph nodes involved in different types of follicular centre cell-derived malignant lymphomas. Most of the Leu 7+ cells in the follicles expressed the Leu 3 (helper/inducer) marker. Double staining studies of tonsil sheep erythrocyte-rosetting and peripheral blood mononuclear cell suspensions showed that two main, mutually complementary, subpopulations of Leu 7+ cells could be distinguished in both cases, namely Leu 7+/Leu 4+ (subdivided into Leu 2+ (suppressor/cytotoxic) and Leu 3+) and Leu 7+/Leu 4-, including mostly cells with OKM 1 (myelomonocytic) characteristics. Thus, in the tonsil cell suspension the cells with Leu 7+ Leu 3+/OKM 1- immunophenotype strongly predominated, whereas among peripheral blood mononuclear cells Leu 7+Leu 2+/OKM 1- and Leu 7+/OKM 1+ immunophenotypes were mostly observed.     

S-100 protein positive human T-lymphocyte

S-100 protein was detected in a small number of human peripheral T-lymphocytes by a direct immunoperoxidase method with the use of monospecific antibody to S-100 protein. Complemented-mediated lysis using monoclonal antibodies revealed that the S-100+ T-lymphocytes bore OKT3, OKT8, and OKT11 antigens but not OKT4, OKM1, HLA-DR, HNK1 (Leu-7) antigens on their surface. Immunoelectron micrography showed that S-100 T-lymphocytes were small lymphocytes with poorly developed cellular organelles. These findings clearly indicated that S-100+ T-lymphocytes belonged to the OKT8+ T-cell subset, the so-called suppressor/cytotoxic T-cell subset. Although the function of the S-100+ T-lymphocytes is unclear, S-100 protein may be a useful cytoplasmic marker for the subdivision of the heterogeneous OKT8+ lymphocyte population.     

In situ immune complexes, lymphocyte subpopulations, and HLA-DR-positive epithelial cells in Hashimoto thyroiditis

Surgical specimens from thyroid glands from seven patients with Hashimoto thyroiditis and two patients with non-autoimmune colloid goiter were analyzed by immunohistologic techniques (direct and indirect immunofluorescence and immunoperoxidase tests) using polyclonal antisera against total immunoglobulin, Ig classes (IgM, IgD, IgG, and IgA), and complement component C3 and monoclonal antibodies specific for B cells, T cell subpopulation, macrophages, natural killer cells, granulocytes, and HLA-DR antigen. Complement-fixing immune complexes (IgG+, C3+) were noted predominantly in areas with only slight destruction and only moderate lymphoid infiltration of thyroid follicles. In areas with intense lymphoid infiltration of thyroid follicles, where many well-developed germinal centers and significant perivascular lymphoid infiltration were seen, immune complexes were scarce. In these latter areas T helper cells (OKT4+, Leu3a+), were more abundant than T cytotoxic/suppressor cells (OKT8+), macrophages (OKM1+), and plasma cells (IgG+); only a few B lymphocytes (smIgM+, smIgD+), granulocytes (ViMD5+), and natural killer cells (VEP13+, Leu7+) were noted in the interstitium between thyroid follicles, intruding between thyroid follicular epithelial cells and merging into the thyroid follicular lumen. Many activated T cells (OKT10+, HLA-DR+) were present in these areas of advanced destruction. HLA-DR antigen expression was seen on macrophages, tissue reticulum cells, vascular endothelial cells, lymphoid cells, and, most interestingly, on thyroid epithelial cells. Normal thyroid epithelial cells did not express HLA-DR. Only a few epithelial cells in the vicinity of lymphoid infiltrations were HLA-DR+ in early stages of Hashimoto thyroiditis, and the number of HLA-DR+ epithelial cells was significantly increased in advanced stages of the disease. In our present report the potential role of HLA-DR+ thyroid epithelial cells for the in situ stimulation of the immune system within the thyroid gland of patients with Hashimoto thyroiditis is discussed, and it is hypothesized that HLA-DR+ thyroid epithelial cells may be an important factor for the progression and self-perpetuation of the disease, which is probably initiated by humoral components of the immune system but further propagated by cellular immunopathologic mechanisms.     

Lymphomatoid papulosis. Characterization of skin infiltrates by monoclonal antibodies

Cryostat sections from fully developed papular lesions of lymphomatoid papulosis (histologic subtype A or B) have been examined by immunoenzymatic staining with 24 monoclonal antibodies against lymphoid cells and their subsets. The lesions demonstrated essentially identical cellular compositions and consisted of T-lymphocytes with a peripheral phenotype (Lyt3+, anti-Leu-4+, OKT6-), macrophages (HLA-DR+, EB11+, OKM1+), and Langerhans cells (HLA-DR+, OKT6+). T-helper/inducer cells (anti-Leu-3+) usually dominated over T-suppressor/cytotoxic cells (anti-Leu-2+). In all cases, proportions of the infiltrating T-cells expressed markers associated with activation (HLA-DR, the OKT1O antigen, interleukin-2 receptor) or proliferation (transferrin receptor, the Ki-67 antigen) of lymphoid cells. Furthermore, the infiltrates contained clusters and/or sheets of large cells reactive with antibodies (Ki-1, Ki-24, Ki-27), which recognize Hodgkin's and Reed-Sternberg cells. These data indicate an origin of the cellular infiltrate from transformed or activated lymphoid cells and suggest an interrelationship of lymphomatoid papulosis to Hodgkin's disease.     

Leu M1 and peanut agglutinin stain the neoplastic cells of Hodgkin's disease

It has been suggested that the malignant cells of Hodgkin's disease (HD), Reed-Sternberg cells, and their mononuclear variants may be related to cells of the monocyte-histiocyte system. To test this hypothesis, 20 cases of HD were tested with nine antibodies, monoclonal or polyclonal, that normally react with cells of monocytic/histiocytic/granulocytic lineages, as well as PNA, which binds to histiocytes directly. Only two reagents, Leu M1 and PNA bound to the neoplastic cells in 20/22 and 13/22 cases tested, respectively. Leu M1 was the most sensitive reagent and was negative in only two cases of lymphocyte predominant HD. Leu M1 also could be employed in routinely fixed and processed formalin or B5-fixed tissue. This antibody, which was negative in 27 cases of non-Hodgkin's lymphoma, including 12 peripheral T-cell lymphomas, should prove to be of value in differential diagnosis of HD and morphologically similar reactive and neoplastic lymphoid lesions.     

Distribution of lymphocyte subsets in a case of angiofollicular lymph node hyperplasia

A series of monoclonal and polyclonal antibodies was used to determine the distribution of lymphocyte subsets in frozen tissue sections of a case of angiofollicular lymph node hyperplasia (ALNH), intermediate type. Primary follicles and mantle zones of secondary follicles consisted of BA1+OKIa1+-C3RTo5+sIgM+sIgD+ lymphocytes. Poorly developed follicular centers reacted with OKIa1, C3RTo5, DRC-1 and anti-IgM but contained no OKT4+Leu-3a+ or Leu-7+ cells. Mantle zones and primary follicles contained more OKT4+Leu-3a+ and less OKT8+ cells than normally observed. The interfollicular area consisted mainly of OKT4+Leu-3a+OKIa1- helper/inducer T-cells, admixed with some OKT8+ suppressor/cytotoxic T-cells and OKIa1+ interdigitating reticulum cells. Polyclonal plasma cells were found both in follicular centers and interfollicular areas. Based on the analogy to the peripheral lymphoid tissue in nude mice and in children with variable thymic dysfunction, it is suggested that the abnormal distribution of immunoregulatory T-cells may be of pathogenetic significance and may account for the morphology of the lymphoid follicles in ALNH.     

Phenotypes of Human Large Granular Lymphocytes as Defined by Monoclonal Antibodies

Four monoclonal antibodies VEP8, VEP9, VIM-D5, VIB-C5 against antigens expressed on human mature myeloid cells (polymorphonuclear leukocytes [PMNL] and/or monocytes) as well as on immature cells in the bone marrow were tested for reactivity with cell preparations highly enriched for large granular lymphocytes (LGL). These cells are known to be the main effector cells responsible for natural killer (NK) cell activity in human peripheral blood. Using indirect membrane immunofluorescence (IMF), none of these antibodies showed any reactivity at all. In addition, LGL-enriched cell preparations were tested with the anti-lymphocyte monoclonal antibodies OKT6, anti-Leu1, anti-Leu2a, anti-Leu3a, and anti-human Lyt3, and also with OKM1 antibody. Significant reactivity was found with anti-Leu2a (59 ± 8 %), anti-Lyt3 (55 ± 4 %) and OKM1 (81 ± 11 %) antibodies, whereas T6, Leu1, and Leu3a antigens were less pronounced or missing on LGL. As a further approach, another monoclonal antibody, VEP13, which reacts with LGL, granulocytes but not monocytes and is therefore different in its specificity from OKM1 and OKT10, was used for identification of LGL. The coexpression of antigens as defined by the above-mentioned antibodies and OKT10 on VEP13⁺ cells was studied. Again, phenotypes similar to those observed on LGL enriched by Percoll^® gradient centrifugation were found: of VEP13⁺ cells 84 ± 6 % reacted with OKM1, 82 ± 5 % with OKT10, 52 ± 17 % with anti-human Lyt3, and 48 ± 14 % with anti-Leu2a, whereas VEP8, VEP9, VIM-D5, VIB-C5, T6, Leu1, Leu3a antigens were not expressed on VEP13⁺ cells. Taken together as an overall evaluation of phenotypic characteristics, our data indicate that LGL cannot be integrated into one of the known lymphocytic or myelomonocytic lineages. LGL show an intermediate phenotype depending possibly on varying differentiation or activation stages of haemopoietic cells. However, the possibility also exists that LGL belong to a separate, yet undefined cell lineage.     

Two color flow cytometry of lymphocytes from patients with adult T-cell leukemia

Lymphocytes from eight patients with adult T-cell leukemia were analyzed by two color flow cytometry. Monoclonal antibodies (Leu 3 a, Leu 8, Leu 2 a and Leu 15) labelled with fluorescein isothiocyanate or phycoerythrin were used. The purpose was to identify the subsets of the lymphocytes as helper, suppressor/inducer, suppressor or cytotoxic by the surface marker of the cells. All eight patients had antibodies for ATLA. Proviral DNA in the lymphocytes was found in six patients. Summarising the results, OKT4-positive ATL cells were all of the helper T-cell subset, not the inducer subset. OKT8-positive ATL cells were also positive for OKT4 and were all of the cytotoxic T cell subset, not the suppressor subset. In two patients, some ATL cells had both OKT4 and OKT8 on the same cells, especially in the lymph nodes. In our study, ATL cells from eight cases of ATL had all of the helper T subset. These results suggest that the target cells of the human T cell leukemia/lymphoma virus type will be helper T cells.