IL-3 stimulation has no effect on FcγRI surface expression and slightly increases monomeric IgG binding. Ba/F3-expressing cells were starved overnight and subsequently restimulated with IL-3 for 1 hour. (A) FcγRI surface expression on a starved (open histogram) and restimulated (closed histogram) subclone of FcγRI-transduced Ba/F3 cells. Dotted line represents isotype control. (B-D) Binding of monomeric mouse IgG2a (B), human IgG1 (C), or human IgG3 (D) to FcγRI expressing Ba/F3 cells. Open squares represent starved cells, filled squares represent IL-3 restimulated Ba/F3 cells. Similar results were seen in 3 independent experiments. Datapoints represent means of at least 4 replicates. *P < .05, ***P < .001