Study on suppressive effect of staphylococcal enterotoxin B on human peripheral blood mononuclear cells

Objective To study the effect of staphylococcal enterotoxin B(SEB) on human peripheral blood mononuclear cells and to explore whether apoptosis is one of its immunosuppressive mechanism.Methods Human peripheral blood mononuclear cells in vitro were stimulated by different concentrations of SEB(100 μg/ml,50 μg/ml,25 μg/ml,10 μg/ml,5 μg/ml,1 μg/ml,0.1 μg/ml,0.01 μg/ml,0.001 μg/ml and 0.0001 μg/ml).PBMCs in negative control group were cultivated in RPMI1640,and PHA was added in positive control group.After cultivation for 48 h,MTT colorimetric assay was used to analyze proliferation of PBMC.Same process was also carried out in negative control group in RPMI1640 and positive control group of PHA.After 48 h,the repeated stimulation with 10 μg/ml SEB was done on PBMC for two times.Results Different concentrations of SEB could initially stimulate human peripheral blood mononuclear cells in vitro to proliferate,but the proliferation of PBMC activated by 10 μg/ml SEB was most dramatic.There was no significant difference between group of 10 μg/ml SEB and group of PHA.Their rates of proliferation were 23.1% and 24.3% respectively.After repeated stimulation at 48 hr later,PHA could continue to stimulate the proliferation of PBMC,but 10 μg/ml SEB could inhibit the proliferation of PBMC.Conclusion SEB may initially stimulate the proliferation of human PBMC in vitro.The repeated stimulation with SEB may inhibit the proliferation of PBMC.