Inhibition of the immune response by Fc receptor-bound specific antibody on T lymphocytes.

Removal of naturally occurring membrane-bound antibody from the surface of nonadherent spleen cells by pronase enhances the in vitro plaque-forming cell response to sheep erythrocytes, and this enhancement can be abrogated by preincubation of the enzyme-treated cells in anti-sheep red blood cell antibody. This inhibitory effect is specific in that prior absorption with sheep erythrocytes but not with noncross-reacting red blood cells removes the activity from antibody-containing preparations. Whole IgG molecules are necessary to bind to Fc receptor; F(ab')2 fragments do not inhibit. The functionally significant Fc receptor-bound antibody in this system is found on the T lymphocyte.