Characterization of a monoclonal antibody that reacts with an activation antigen on human B cells: reactions on mitogen-stimulated blood lymphocytes and cells of normal lymph nodes.

We describe a monoclonal antibody that reacts with human B-lymphoid cells. We have characterized the reactions of this antibody on normal blood lymphocytes, with and without pokeweed mitogen stimulation, bone marrow lymphocytes, and on frozen sections of normal lymph nodes. The antibody, B532, appears to recognize an activation antigen on human B cells. This activation antigen can apparently be induced both by infection with Epstein-Barr virus and by stimulation with antigens and mitogens, but it is lost on plasma cells. In normal lymph nodes, the antigen is confined to germinal center cells and some of the cells of the "mantle" that surrounds germinal centers. The antigen is not present on T cells.