Two monoclonal antibodies defining unique antigenic determinants on human B-lymphoma cells.

The non-Hodgkin's lymphomas are a clinically, morphologically, and immunologically heterogeneous group of diseases. Why lymphoma cells are unresponsive to normal regulatory growth controls and how they differ from normal lymphocytes are not well understood. In order to address these questions we have raised monoclonal antibodies to neoplastic B-cells. Two of these, LM-26 and LM-155, show a high degree of specificity for B-cell lymphomas. When tested by fluorescence activated cell sorter analysis, LM-26 reacted with 80% (18 of 23) of B-cell lymphomas freshly explanted from patients and LM-155 reacted with 20% (5 of 23). The antigenic determinant detected by LM-26 was also found to be present on four of seven neoplastic large cell B-lymphoma lines. LM-155 detected a determinant present on all seven of these lines. For neither monoclonal antibody was there any association between antibody reactivity and the morphological subtype of lymphoma examined or the type of cell surface immunoglobulin expressed. LM-155 reacted with one case of B-cell acute lymphoblastic leukemia. Neither antibody reacted with normal B-cell blasts, normal peripheral blood mononuclear or marrow cells, T-cell leukemias or lymphomas, or chronic lymphocytic leukemia cells. Lymphocytes from reactive lymphoid hyperplasias involving lymph nodes, spleen, peripheral blood, and lung were also negative for LM-26 and LM-155 binding or showed only a small percentage of cells positive (4-8%). Both monoclonals were unreactive with non-B-lymphoid neoplastic cell lines, nine of ten Epstein-Barr virus transformed B-cell lines, and cells freshly explanted from patients with cancers of diverse cellular origins. Fluorescence activated cell sorter analysis of the expression of the antigens defined by LM-26 and LM-155 on lymphoma cells and normal B-cell blasts suggests that they are not normal differentiation antigens associated with lymphocyte activation or proliferation. The highly restricted expression of detectable levels of antigens reactive with monoclonal antibodies LM-26 and LM-155 on non-Hodgkin's lymphoma cells suggests a possible relation to their neoplastic properties. From a practical viewpoint these monoclonals may prove useful in the diagnosis, classification, detection of residual disease, and treatment of the non-Hodgkin's lymphomas.