Fig. 4.

Purified complement proteins C1q, C2, C3, and C4 added to the indicated complement-depleted (Dpl) serum can restore HCV binding to B cells. Ten million genomic copies of HCV 1a (H77s) in 3 ml medium were incubated with 100 µl of the indicated complement-depleted serum sample or complement-depleted serum sample plus the indicated purified complement protein, or purified complement protein only. After 1h incubation at 25°C, 2 ml PBMCs (2.5×10⁷ cells per ml) in complete RPMI medium was added. The reaction was carried out at room temperature (25°C) for 1 h. The cells then were processed for HCV quantification as described in Methods section. All experiments were repeated twice with similar results using PBMCs from two different donors. Each value represents the mean ± SD of 6 determinations.