FIG. 2.
Cytokine induction by PPVO (virus titer, 104.6/ml). ConA was used in PBMC (106 cells/ml) at a concentration of 1 μg/ml and in whole blood (WB) at a concentration of 12 μg/ml. RPMI 1640 medium served as a negative (neg.) control (contr.). (A) TNF-α is induced in PBMC and WB. Costimulation with ConA caused an increase in TNF-α secretion in WB but not in PBMC. Cells were cultured for 24 h. (B) IL-8 is induced in PBMC and WB. Costimulation with ConA had no effect. Cells were cultured for 4 h. Differences between IL-8 levels in PBMC and WB might be due to high-affinity binding of IL-8 to erythrocytes. (C) IL-6 is released in PBMC and at slightly lower levels in WB. This difference might be caused by a higher level of nonspecific binding of IL-6 in WB. Cells were stimulated for 4 h. Costimulation with ConA had no effect. (D) IL-10 is induced in PBMC and WB. Cells were incubated for 24 h. Costimulation with ConA had no effect. (E) IL-1ra is induced in WB. Costimulation with ConA had no effect. Cells were cultured for 24 h. IL-1ra was not measured in PBMC. (F) Small amounts of IL-18 are induced in WB. The induction was slightly increased by ConA costimulation. Cells were incubated for 24 h. IL-18 was not measured in PBMC. (G) IL-4 is released in PBMC and at higher levels in WB with ConA costimulation. IL-4 was measured in the same supernatants as IFN-γ. PBMC were cultured for 4 days, and WB was cultured for 3 days. IFN-γ was the dominating cytokine (data not shown). (H) IL-12 is induced in small amounts but only in WB and only with ConA costimulation. Cells were incubated for 24 h.