Determination of a 45 Kda leukocyte common antigen and its unique expression on B cell development
A murine monoclonal antibody (MAb) designated as IF2 directed against a common and broad molecule expressed on leukocytes has been generated by fusing X.63 Ag.8653 (Mouse myeloma cell line) with spleen cells from mice immunized with purified human T cells. The MAb secreted by the selected hybridoma was screened on different tissues such as thymus, tonsils and skin by immunoperoxidase staining and on normal T cells, B cells (E rosette negative cells), eosinophils, leukemic cells, T cell lines (JURKAT and HPBALL), burkitt’s lymphoma cell lines (DAUDI, RAMOS and BJAB) and a monocytic cell line U937 by indirect fluorescent test. Data indicated that, except for 2 pre B cell lines, the epitope recognized by 1F2 MAb was found to be broadly expressed on human leukocytes. Western blot analysis indicated that 1F2 MAb recognizes a 45 KDa molecule from a cell lysate of U937 and of JURKAT cell lines but not from that of the NALM6 cell line. The comparison of these data with those previously reported to the human leukocyte workshops indicated that 1F2 MAb may have recognized an epitope with a broad specificity on lymphoid and on myeloid tissues similar to the tissue distribution pattern which has been documented for those MAbs clustered in CD48 antigens. The results in respect to the application of most MAbs clustered in this group for bone marrow purging are discussed.