PRODUCTION OF 2 MONOCLONAL-ANTIBODIES (FB1 AND FB21) USEFUL FOR THE IDENTIFICATION OF HUMAN B-LYMPHOCYTES IN FORMALIN-FIXED, PARAFFIN-EMBEDDED TISSUES

Two monoclonal antibodies (FB1 and FB21) reactive in formalin-fixed, p araffin-embedded tissue sections are reported in this paper. FB1 and F B21 recognize a cytoplasmic antigen and a surface antigen of B cells, respectively. FB1 reacts with mantle zone (MZ) B cells, germinal centr e (GC) cells, and marginal zone (MrZ) B cells, but not with T cells in lymphoid tissues. FB21 reacts with MZ B cells, GC cells in lymphoid t issues, and T cells of peripheral blood, but not with MrZ B cells in t he spleen. Neither monoclonal antibody (MoAb) reacts with monocytes, g ranulocytes, or plasma cells. FB1 reacted with all the B-cell lymphoma s tested and with CD20-positive Reed-Sternberg cells in two of five ca ses of Hodgkin's disease, but not with multiple myelomas or T-cell lym phomas. FB21 reacted with B-cell lymphoma in 20 of 22 cases, but not w ith multiple myelomas, T-cell lymphomas, or Reed-Sternberg cells of Ho dgkin's disease. Immunoprecipitation studies revealed that FB1 recogni zes the same two polypeptide chains that are recognized by L26 and is a member of the CD20 antibody cluster. FB21 was thought to recognize a sialic acid-dependent carbohydrate epitope and this was confirmed at the Fifth International Conference on Human Leukocyte Differentiation Antigens (Boston, 1993). FB21 did not react with splenic MrZ B cells a nd was different from the pan B markers reported previously [CD20 (L26 ), CD45RA (MB1), and CD74 (LN-2)]. FB21 recognizes a subset of B cells and appears to be closely related to CD75/76 antibodies. FB1 and FB21 are useful MoAbs for the diagnosis and analysis of B-cell lymphomas.