supernatant of normal PBMC Cultured tured by adding serum from patientswith active idiopathic nephrotic syndrome（INS） serving as soluble immune responsesuppressor（SIRS）was detected in 10 cases.The influence of SIRS on IL-6 activity

IgG and IgG subclasses productions in vitro in normal PBMC was observed.The resiiltsshowed that the productions of IgG

IgG

1

and IgG

2

in normal PBMC induced by PWMwas sigiiiflcantly decreased but not IgG

3

when SiRS was add ed in the culture systemand there was a significant correction between inhibited productions of IgG and IgG

1

.Itis likely that serti[n from INS patients induces Ts cell to secrets SIRS which inhibites Bcell differentiation and IgG isotype switch.and that the presence of SIRS may be relatedto the pathogenesis of hypoimmunoglobulinemia G in active INS patients.