Effect of cellular activation on immune complexes binding to saturated FcγRI. (A) Binding of Ba/F3-FcγRI to huIgG3-opsonized RBCs (y-axis) after incubating Ba/F3-FcγRI with varying amounts of monomeric huIgG3 (x-axis). Dotted line represents binding of Ba/F3-FcγRI to unopsonized RBCs. (B) Percentage of Ba/F3-FcγRI binding to RBCs. One representative sample of triplicates is shown. (C) Amounts of cell-bound Ba/F3-FcγRI IgG3 after incubation with varying amounts of monomeric human IgG3 as detected by flow cytometry. Experiments were repeated 3 times yielding similar results.