Antigenic characterization of murine rosette and plaque-forming cells.

Specific antisera reacting with mouse B and T lymphocytes were raised by immunizing rabbits with: (1) mouse myeloma tumour cells; (2) bone-marrow cells; (3) thymus cells, and proper absorptions of the antisera obtained. These antisera together with anti-IgG and anti-θ 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 the action of all types of antibody-producing cells, i.e. direct and indirect PFC, and normal and 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-θ, did not inhibit PFC, and occasionally inhibited a small percentage of RFC. With the aid of these heterologous antisera at least three 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 tumour cells.