Interleukin (IL)-2 and IL-3 induce distinct but overlapping responses in murine IL-3-dependent 32D cells transduced with human IL-2 receptor beta chain: involvement of tyrosine kinase(s) other than p56lck.

We have established IL-3-dependent 32D myeloid progenitor cells stably expressing the human IL-2 receptor beta chain (IL-2R beta). Whereas parental 32D cells proliferated only in response to IL-3, the transduced cells also proliferated in response to IL-2. Transduced cells expressed high- and intermediate-affinity IL-2Rs, resulting from expression of human IL-2R beta and murine IL-2R alpha chain (IL-2R alpha). IL-2 induced phenotypic changes not induced by IL-3, including the upregulated expression of endogenous murine IL-2R alpha and IL-2R beta and an increase in cell size. Therefore, the transduced IL-2R beta was not merely coupling with the IL-3 signaling pathway. IL-3 augmented several IL-2-induced responses including the up-regulation of IL-2R alpha. Both IL-2- and IL-3-induced proliferation and IL-2 induced IL-2R alpha expression were inhibited by the tyrosine kinase inhibitor herbimycin A. Thus, both IL-2- and IL-3-mediated effects required tyrosine kinase activity. The identity of the tyrosine kinase(s) mediating the IL-2 signals in these cells is not known but cannot be p56lck, a tyrosine kinase found in T cells, since 32D-IL-2R beta cells do not express p56lck.