Interleukin 4 (IgG1 induction factor): a multifunctional lymphokine acting also on T cells.

A cDNA encoding the murine interleukin 4 (IL4) (IgG1 induction factor/B cell-stimulating factor no. 1) was recently cloned (Noma et al., Nature 1986.319: 640; Lee et al., Proc. Natl. Acad. Sci. USA 1986. 83: 2061). In this report we tested recombinant IL 4 in various T cell assays. It was found that IL 4 activated the murine T cell line CTLL to increased DNA synthesis but not to growth. It also activated normal concanavalin A (Con A)-stimulated T cells both to increased DNA synthesis and to growth. These T cell growth factor-like activities were not inhibitable by anti-IL 2 receptor antibodies. Evidence is given that both Lyt-2+ and L3T4+ T cells responded to IL 4. Finally, IL 4 acted synergistically with phytohemagglutinin or Con A on normal T lymphocytes as well as on thymocytes. These data, as well as those of others, imply that lymphokines have a broader range of activity than previously anticipated.