Flow cytometric analysis of the binding of rE2 to human cell lines and platelets.

(A) Molt-4 cells, U937 cells, and platelets were incubated with rE2, and cell-bound protein was detected by flow cytometry with a mouse mAb to E2 and FITC-conjugated rabbit antibodies to mouse IgG (shaded profiles); as a control, the mouse mAb to E2 was replaced with an IgG isotype control (open profiles). (B) The recombinant E2 protein was incubated in the absence or presence of E2-reactive IgG from an HCV-infected patient or of control human IgG before addition to target cells. The binding of rE2 to cells was then determined by flow cytometry as in panel A. Data are expressed as median fluorescence intensity and are representative of 3 to 5 separate experiments.