EFFECT OF INTERLEUKIN-10 ON NF-KB AND AP-1 ACTIVITIES IN INTERLEUKIN-2 DEPENDENT CD8 T-LYMPHOBLASTS

Interleukin-10 is a multifunctional cytokine, which regulates the func tion of various cell types of the immune system. In CD8 T cells it is known to accelerate the interleukin-2 dependent proliferation and to i nduce the differentiation of these cells to active cytolytic cells. No w we have studied interleukin-10 induced intracellular signaling mecha nisms in human interleukin-2 dependent CD8 T lymphoblasts. The data ob tained demonstrate that interleukin-10 alone can activate the AP-1 tra nscription factor and potentiate the interleukin-2 induced NF-kappa B activity. Moreover, interleukin-10 induced a rapid tyrosine phosphoryl ation of several proteins. The pattern of proteins phosphorylated was very similar to that induced by interleukin-2. Together, these finding s suggest that tyrosine kinase dependent activation of NF-kappa B and AP-1 transcription factors are involved in the signaling mechanism of interleukin-10. This activation pathway resembles that of interleukin- 2 in the same cell type.