INTERLEUKIN-1-ALPHA-STIMULATED FIBROBLAST EICOSANOID SYNTHESIS IS NOT MEDIATED BY INTERLEUKIN-6

Adherent human dermal fibroblasts secreted interleukin-6, prostaglandin E2, prostaglandin I2 and 15-hydroxyeicosa-tetraenoic acid (assayed by radioimmunoassay) during a 3 h incubation period. Although human dermal fibroblasts did not secrete interleukin-1-alpha or interleukin-1-beta, human recombinant interleukin-1-alpha stimulated arachidonic acid metabolism and interleukin-6 synthesis. This effect was, at least partly, dependent on de novo protein synthesis. In contrast, human recombinant interleukin-6 had no effect on the synthesis and release of the eicosanoids measured. Human recombinant interleukin-1-alpha also stimulated the metabolism of [C-14]arachidonic acid, but only if fibroblast were pre-incubated with the cytokine for three hours. Our data indicate that (a) fibroblasts secrete interleukin-6 but not interleukin-1, (b) interleukin-1-alpha, but not interleukin-6, stimulates fibroblast arachidonic acid metabolism and (c) the mechanisms involved in the metabolism of endogenous arachidonic acid are more sensitive to human recombinant interleukin-1-alpha than those involved in metabolism of the exogenous substrate.