Interleukin 3 (IL-3)-induced FcαR activation is independent of association with the Fc-receptor (FcR) γ chain.

The effect of cytokine stimulation on immunoglobulin A (IgA) binding was investigated in Ba/F3 cells expressing the FcαR_R209D mutant, which is unable to interact with the FcRγ chain. Cells were cytokine-starved for 4 hours and treated for 15 minutes with IL-3 (gray bars) or left untreated (white bars), and subsequently IgA-binding assays were performed. Binding of IgA beads was scored under a microscope, and results are expressed as rosette index (number of beads/100 cells) and as means ± SE (n = 3).