FIG. 3.

Inhibition of E2 binding to KM3-CD81 cells by anti-CD81 MAbs. RBL-CD81 cells were incubated with MAb W6-32 (anti-MHC class I) or MAbs 5A6, ID6, JS81, 4TM-1, and 1.3.3.22 (anti-CD81) at concentrations known to saturate the cell surface for 1 h. Unbound MAb was removed by washing, and the cells were evaluated for the ability to bind soluble E2₆₆₁ (open graphs) or mock (shaded graphs). Cell-bound antigen was visualized with MAb 11/4b, anti-rat IgG-PE, and FACS analysis. Mock and E2 antigen failed to bind to the parental RBL cells in the same experiment, giving a background median FI of 3.5.