Effect of whole-body irradiation on precursor frequency of autoantibody-secreting cells and plaque-forming cells specific for bromelain-modified erythrocytes.

Murine spleen cells and peritoneal cells were assayed for autoantibody production against bromelain-modified mouse erythrocytes (mouse brom-RBC) after whole-body irradiation at a dose of 5 Gy. Spleens were taken directly from mice 3 days after irradiation, or cultured for 3 days 24 h after irradiation, and assayed. Cells taken directly from irradiated mice had a higher number of plaque-forming cells (PFC) against mouse brom-RBC, compared with unirradiated mice, when the data were expressed as PFC/10(6) viable cells. This apparent increase can be accounted for by the reduced number of cells in the spleens from irradiated mice. In both spleen cells and peritoneal cells cultured in high cell densities, no difference was observed in the number of PFC in cells from irradiated or unirradiated mice. The detected precursor frequency of autoimmune B cells in both cell populations cultured in limiting dilution was found to be lower in cells from irradiated mice. In contrast to other published data, it was concluded from these investigations that whole-body irradiation, at a dose of 5 Gy, does not augment autoantibody production against mouse brom-RBC. It is proposed that the reason for this is the presence of a regulatory cell that is relatively radioresistant and, hence, not removed after whole-body irradiation at a dose of 5 Gy.