B cells express CD81, SR-BI, and C-type lectins DC-SIGN and L-SIGN. (A) HCV viral receptor expression on untreated or CD40L/IL-4–stimulated PBMC-derived primary B cells, and L3055–Bcl-2 was characterized by flow cytometry. Median fluorescence intensity (MFI) values are plotted for isotype controls (■), CLDN1 (), SR-BI (), and CD81 (□) as an average from 3 tests, with error bars showing the SD (B) 20 μg total cellular protein from Huh-7.5 (lane 1); B cell–depleted fraction from BD1 (lane 2) and BD2 (lane 3); resting (lane 4) and CD40L/IL-4–stimulated PBMC-derived B cells (lane 5) from BD1; resting (lane 6) and CD40L/IL-4–stimulated PBMC-derived B cells (lane 7) from BD2 were separated by SDS-PAGE; the proteins were transferred to PVDF membranes and probed for SR-BI and actin expression. (C) Summary table of DC-SIGN/L-SIGN expression in untreated and CD40L/IL-4–stimulated PBMC-derived primary B cells and L3055–Bcl-2.