Regulation of thymus-independent responses: unresponsiveness to a second challenge of TNP-Ficoll is mediated by hapten-specific antibodies.

CBA mice immunized with the TI-2 antigen TNP-Ficoll are unresponsive to a second challenge of the same antigen. In addition, spleen cells from unresponsive mice fail to respond to any dose of TNP-Ficoll in vitro. This hapten-specific unresponsive state is T cell independent and is due to hapten-specific IgM-mediated inhibition of B cell triggering. The mechanism of inhibition, although unknown, is unlikely to be antigen masking. In vitro responses to the TI-1 antigen TNP-LPS are not inhibited by concentrations of anti-TNP antibody, which completely suppress responses to TNP-Ficoll.