Fig. 3.

Effects of gradual reconstitution of C4-deficient serum on IA-induced cytokine production. Sera were incubated without or with increasing amounts of C4 together with HAGG or mIgG (100 µg/ml final concentration in SN) for 20 min in 37°C. The mixtures (final serum concentration 10%) were then added to PBMC cultures (10⁶/ml) from four healthy donors. After 20 h SN were collected and levels of IL-10 and IL-12p40 determined by ELISA. Filled symbols show the results of C4 addition to the C4-deficient serum, whereas open symbols represent the results of C4 addition to a complement sufficient normal serum. Results are shown as differences in cytokine production between cultures stimulated with HAGG and mIgG, with a positive value signifying higher cytokine levels in HAGG culture SN compared to mIgG SN. A separate graph shows the effect on the function of the classical complement pathway after addition of increasing amounts of C4 to the C4 deficient serum.