Impaired regulation of erythrocyte autoantibody production after splenectomy.

C3H mice were given 4 i.p. injections, eac of 2 X 10(8) WAG rat RBC, at weekly intervals. The production of erythrocyte autoantibodies elicited by the cross-reacting rat RBC was assessed using the average direct Coombs' test (DCT) score. Autoantibody production reached higher levels and persisted significantly longer in mice splenectomized 15 days before the first injection of rat RBC. This increased production of autoantibodies was not prevented by injecting each splenectomized mouse i.v. with 5 X 10(7) syngeneic spleen cells immediately after splenectomy. Similarly, splenectomy of mice already DCT+ significantly prolonged autoantibody production which was not prevented by injections of 10(8) cells prepared from the spleens removed at splenectomy. Transfer of spleen cells from mice already DCT+ to mice before the injections of rat RBC were started in the recipients caused a significant reduction in the amount of RBC autoantibodies produced. This suppression of autoantibody production was greater in unsplenectomized mice than in splenectomized mice. The results show that the spleen is involved in the regulation of these erythrocyte autoantibody responses. It is hypothesized that, in addition to the cellular component of the spleen, the splenic architecture and/or environment contributes to the regulation of autoantibody responses.