The suppressive effect of antibodies on cellular cooperation.

1) The primary and secondary anti-carrier antibody responses were markedly suppressed by the passively administered anti-carrier antibody but not by the anti-hapten antibody. 2) The primary and secondary anti-hapten antibody responses were suppressed not only by the passively administered anti-hapten antibody but also by the anti-carrier antibody. 3) Passively administered 3.5S fragments of the anti-carrier antibody selectively suppressed the anti-carrier antibody response but had no effect on the capacity of carrier-specific helper T cells to facilitate the anti-hapten antibody response. 4) Passively administered anti-carrier antibodies did not suppress the development of carrier-specific helper T cells but suppressed B memory cells specific for the haptenic group as well as the carrier determinant.