Direct blockade of antigen-reactive B lymphocytes by immune complexes. An 'off' signal for precursors of IgM-producing cells provided by the linkage of antigen-and Fc-receptors.

Antigen-antibody complexes efficiently inhibit the induction of antibody formation. Using Mishell-Dutton cultures, it can be demonstrated that neither T cells nor their products are required for this inhibition of IgM PFC formation. The blockade is at the level of B cells and cannot be overcome by LPS or TRF. The data demonstrate that cross-linking of antigen- and Fc-receptors by antigen-antibody complexes is a blocking signal for B cells.