Interleukin 5 and interleukin 3 induce serine and tyrosine phosphorylations of several cellular proteins in an interleukin 5-dependent cell line.

Murine interleukin 5 (IL-5), a lymphokine produced by helper T cells, is involved in the regulation of growth and differentiation of B cells and eosinophils. To elucidate the intracellular events via the IL-5 receptor, we have investigated IL-5-induced protein phosphorylation in an IL-5-dependent murine early B-lineage cell line (T88-M). The rapid phosphorylation of a 60-kDa protein at serine residues and of 140-, 92-, 53-, 48-, and 45-kDa proteins at tyrosine residues were induced by the stimulation of T88-M cells with IL-5. T88-M cells were found to proliferate in response to IL-3 as well as IL-5, and the phosphoproteins in T88-M cells could be induced by IL-3 stimulation in a similar manner of those induced by IL-5. Thus, these results suggest that the protein phosphorylation events in T88-M cells may be shared by both pathways via the IL-5 receptor and the IL-3 receptor.