FIG. 10.
A plasma factor is necessary for IFN-γ induction by PPVO. The PPVO titer was 104.6/ml, and ConA was used at a concentration of 12 μg/ml. (A) Decreased IFN-γ induction by PPVO in whole-blood cultures with heat-inactivated plasma (pl. heatinact.), with plasma replaced by RPMI 1640 medium, and with zymosan-treated plasma. Cells were costimulated with ConA and incubated for 3 days. For each category, data from six donors were available, except for replacement of plasma by RPMI 1640 medium, which was performed only for the first two donors. The decrease in IFN-γ induction was significant (the P value, determined by the Wilcoxon test, was <0.05) for cultures with heat-inactivated plasma and for those treated with zymosan. (B) Decreased TNF-α induction in whole-blood cultures with heat-inactivated plasma. TNF-α induction was not measured in cultures treated with zymosan. Cells were stimulated for 24 h.