Studies on immunosuppression by cobra venom factor. II. On responses to DNP-Ficoll and DNP-Polyacrylamide.

We have reassessed the effects of CVF administration on the humoral responses to two T-independent immunogens: DNP-Ficoll and DNP-Polyacrylamide. With high immunogen doses, little or no evidence of suppression was found. However, when the immunizing dose was reduced, suppression of both IgG and IgM responses became apparent. As indicated in a previous report, the immunosuppressive effect of CVF on T-dependent responses may result not only from C depletion but also from the generation of C cleavage products that may impair the auxiliary contribution of macrophages to the generation of these humoral responses. A similar mechanism may be applicable to the suppression of antibody production to DNP-Ficoll and DNP-PAA in view of recent reports showing a macrophage requirement for the response to these immunogens.