Cytokine-induced activation of FcR in Ba/F3 cells.

Immunoglobulin A (IgA)-binding assays were performed with Ba/F3_FcαR cells. In (A), the binding of IgA beads to Ba/F3_FcαRwt cells was compared with that of untransfected cells (Ba/F3). To study the effect of interleukin 3 (IL-3) on IgA binding, cells were washed and resuspended in IL-3-free medium with 0.5% fetal calf serum. In (B), time points indicate the period of IL-3 withdrawal prior to performing the assay (n = 2). In (C), the effect of IL-3 addition is shown, and the time points indicate for how long cells were stimulated with IL-3 prior to being incubated with IgA beads (n = 3). Subsequent to cytokine stimulation, IgA binding was performed. In all panels, results are expressed as rosette index (number of beads/100 cells) and as means ± SE.