Regulation of immune response to SRBC: suppressor cell activity induced by soluble fraction of antigen

Water soluble fraction (SF) of SRBC was obtained by hypotonic lysis and ultracentrifugation. SF was found to induce very weak SRBC-specific antibody response in mice. Pretreatment with SF accelerated direct PFC response to SRBC and accelerated and suppressed indirect PFC response. Spleen cells from mice treated with SF exhibited enhanced response to SRBC after transfer in irradiated recipients. The transfer of spleen cells from mice treated with SF to normal non-irradiated mice markedly suppressed the recipients' PFC responses to SRBC. The observed suppressive effect is interpreted as a consequence of suppressor cell activity.