[Studies on the mechanism and duration of antibody-mediated immunosuppression (author's transl)].

The simultaneous injection of either 10(8) or 5 X 10(5) sheep erythrocytes (SE) and an allogeneic anti-SE serum into mice produced not only a suppression of the primary immune response, but, moreover, the secondary immune reaction elicited, either 4, 8, 12, 16 or 30 weeks after the primary antigenic stimulation, was found to be impaired. This was mainly demonstrated by the significantly reduced numbers of 7 S antibody-synthesizing spleen cells. The suppression of the secondary immune responses is hardly compatible with the conception that the antibody-mediated immunosuppression is solely due to an inactivation of the antigenic determinants by the passively administered specific antibody in the periphery of the immune system. This objection against the so-called "peripheric theory" is supported by a further finding. When mice primarily immunized by a simultaneous injection of 10(8) SE and anti-SE-serum were treated with 2 X 10(7) SE 24 hours before boostering with 10(8) SE, in order to eliminate a possibly existing residual activity of the passively administered specific antibodies given together with the primary antigenic stimulus, the secondary 7 S response was likewise found to be significantly suppressed. On the basis of these findings it is suggested that besides the "peripheric mechanism" a "central" effect plays a significant role in the phenomenon of antibody-mediated immunosuppression, this being due to the reversible or irreversible inactivation of immunocompetent precursor cells by the attachment of antigen-antibody-complexes which results in an inhibition of their differentiation into antibody-producing cells.