Antigenic characterization of murine rosette and plaque forming cells

Specific antisera reacting with mouse B and T lymphocytes were raised by immunizing rabbits with mouse myeloma tumour cells; bone marrow cells; and thymus cells, and proper absorptions of the antisera obtained. These antisera together with anti IgG and anti theta were used to characterize surface antigens on antibody producing cells. It was found that anti bone marrow serum, absorbed with thymus cells in the presence of guinea pig C, completely inhibited in vitro the action of all types of antibody producing cells, i.e. direct and indirect PFC, and normal immune RFC. Anti myeloma serum absorbed with thymus cells inhibited direct and indirect PFC, most of the immune RFC, but did not inhibit normal RFC. Absorption with both thymus and bone marrow cells rendered the anti myeloma serum specific for an antigen present on PFC and myeloma cells (My antigen). Anti IgG completely inhibited both normal and immune RFC but had only a minor inhibitory effect on PFC. On the other hand, antithymus absorbed with bone marrow cells, like anti theta, did not inhibit PFC, and occasionally inhibited a small percentage of RFC. With the aid of these heterologous antisera at least 3 antigenic determinants could be defined on the surface of antibody producing B lymphocytes: B1, B2 and My. Thus, normal RFC were shown to be antigenically different from immune RFC and both lack an antigen present in PFC. In addition, all these cells contained the B1 antigen, which was partially or completely missing from myeloma tumor cells.