The role of arachidonic acid metabolism in IL-3-induced proliferation

Two pathways of signal transduction are activated in the same cell by different cytokines

NFS60, a murine leukemia cell line, responds to both interleukin 3 and 6 by proliferating, apparently by different signal transduction pathways. Although stimulation by both cytokines increases the uptake of 3H-arachidonic acid, the response to IL-6 was much faster. Furthermore, the effect of various arachidonic acid metabolites on the response to cytokine was different. PGE2 inhibited IL-6-induced proliferation and potentiated the response to IL-3. Additionally the G proteins which coupled the IL-3 and IL-6 receptor to the proliferative response are probably different, based on the ability of cholera toxin to inhibit the IL-3 but not the IL-6 response. These data are evidence of two pathways of signal transduction.

The effect of dual inhibitor, SK&F 86002, on helper T cell functions

SK&F 86002, a mixed cyclooxygenase-lipoxygenase inhibitor, was examined for its effects on helper T cell functions. The drug was found to inhibit concanavalin A-induced mitogenesis of splenic T cells (IC50 = 13 microns), the mixed lymphocyte response (IC50 = 16 microM), and proliferation of antigen specific T cells (cloned line, IC50 = 11 microM; uncloned line, IC50 = 13 microM). In contrast, another mixed cycloxygenase-lipoxygenase inhibitor, BW775c, did not have such effects at non-cytotoxic levels. These T cell functions are believed to be dependent on the effects of elaborated IL-1. SK&F 86002 has been shown to inhibit the production of mature IL-1 (IC50 = 1 microM), possibly accounting for the anti-inflammatory effects of the drug in rheumatoid arthritis models. In an in vivo model of contact sensitivity, SK&F 86002 was able to inhibit mouse footpad swelling, demonstrating additional anti-inflammatory activity. As an inhibitor of IL-1 synthesis or release, SK&F 86002 may be useful for the treatment of T cell-dependent inflammation.