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A B S T R A C T A monoclonal antibody (anti-B 1) specific for a unique B cell surface differentiation antigen was used to characterize the malignant cells from patients with leukemias or lymphomas. All tumor cells from patients with lymphomas or chronic lymphocytic leukemias, bearing either monoclonal K or X light chain, expressed the Bl antigen. In contrast, tumor cells from T cell leukemias and lymphomas or acute myeloblastic leukemias were unreactive. Approximately 50% of acute lymphoblastic leukemias (ALL) of non-T origin and 50% of chronic myelocytic leukemia in blast crisis were also anti-Bl reactive. Moreover, 21 of 28 patients with the common ALL antigen (CALLA) positive form of ALL were anti-B1 positive, whereas 0 of 13 patients with CALLA negative ALL were reactive.These observations demonstrate that an antigen present on normal B cells is expressed on the vast majority of B cell lymphomas and on -75% of CALLA positive ALL, suggesting that these tuimors may share a common B cell lineage.

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Multiple interactions between T and B lymphocytes are required for generation of the immune response. In large part, these interactions appear to require direct cellcell contact. Therefore, determination of the precise location of T and B ceils within lymphoid structures is of considerable importance. In laboratory animals, approaches utilized to define the anatomic relationship of lymphocyte subpopulations have included determination of the effects of thymectomy on lymphoid architecture (1), study by autoradiography of localization of intravenously injected radiolabeled T and B cell populations (2-4), and immunofluorescence studies of lymphoid tissue employing specific heteroantisera (5). Such studies have provided evidence for a general anatomic compartmentalization of lymphocyte subpopulations. Thus, within lymph nodes, B cells predominate in follicular areas, whereas T cells comprise the predominant cell type in the paracortical areas. In man, immunofluorescence studies of normal lymphoid structures, as well as histologic examination of lymph node tissues from patients with T or B cell deficiency states, have shown similar findings (6-8). These studies have not permitted determination of the location of T cell subsets.Recently, a series of monoclonal antibodies reactive with human thymocyte and peripheral T cell antigens have been developed (9-14). These antibodies allow for the precise characterization of lymphocytes of T lineage. For example, anti-T 1 and anti-T3 antibodies define the entire population of mature peripheral T cells, whereas anti-T4 and anti-T5/T8 are reactive selectively with the inducer and suppressor/cytotoxic subsets, respectively. In addition, a monoclonal antibody termed anti-T6 defines a differentiation antigen expressed on the common thymocyte population but lacking on peripheral T cells. In a prior report, we have employed these antibody probes to localize T cell-associated antigens in the human thymus by immunofluorescence and immunoperoxidase techniques (15). The present study makes use of these monoclonal antibodies, as well as antibodies directed at human IgM and the common framework portion of Ia antigen, to determine the in situ anatomic relationship of immunoregulatory T cell subsets to the B cell-dependent areas in human lymph nodes. Materials and Methods

Cloned human cytotoxic T lymphocytes and monoclonal antibodies inhibiting their function (anti-T3A, anti-T4A, and anti-T8A) were used to elucidate the role of T cell surface glycoproteins in cell-mediated lympholysis involving individual classes of gene products of the major histocompatibility complex on target cells. The results indicate that several surface molecules are required for specific target recognition: T3 and T4 on T4+ cytotoxic T lymphocytes and T3 and T8 on T8+ cytotoxic T lymphocytes.