Suppression of in Vivo Antibody Responses by Suppressor Factors Induced by Human Myeloma Proteins

Suppressor factors induced in vitro, using purified human IgG and IgA myeloma proteins, were shown to efficiently suppress murine antibody production in vivo. The suppression was not isotype specific, viz. IgG and IgA suppressor factors suppressed the production of IgM and IgG antibody. Neither the suppressor factors (SF) nor the inducing proteins suppressed the proliferative responses to concanavalin A and purified protein derivative (PPD). The results are compared to the in vitro findings and discussed in the context of isotype regulation, hypogammaglobulinemia and immunotherapy.