Fig. 5.

Receptors involved in complement-mediated HCV binding to B cells. Two ml of PBMCs (2.5×10⁷ cells/ml) were incubated with 10 µg of the indicated antibody at 25°C for 0.5 h; followed by mixing with 3 ml of activated virus (pre-incubation with serum for 1 h at 25°C, 1×10⁷ genomic copies total), and incubating at 25°C for 1 h. The cells then were processed for RNA isolation and HCV quantification as described in Methods section. **: P < 0.01, ***: P < 0.001, ****: P < 0.0001; when the reduction of HCV binding to B cells by the indicated antibody was compared to antibody isotype control. Each value represents the mean ± SD of 6 determinations. The experiments were repeated three times with similar results using PBMCs from three different donors. CD11b is part of complement receptor 3, CD20 is one of major B cell markers, CD21 is also known as complement receptor 2, CD32 is receptor for Fc fragment of immunoglobulin G, CD35 is complement receptor 1, and CD55 is membrane-bound decay-accelerating factor for convertases of complement system.