IL-1R7 antagonist (Icanomab)

Phorbol ester (TPA) and retinoic acid (RA) are two potent immunomodulatory agents whose actions are mediated through distinct signal transduction pathways involving protein kinase C (PKC) and nuclear RA receptors, respectively. We have investigated the interactions between these two pathways in the regulation of expression of the inflammatory cytokine IL-8 in human skin fibroblasts. TPA (as previously reported) and RA both induced IL-8 mRNA and protein in a time- and dose-dependent manner. IL-8 mRNA induction by TPA (10 nM) was maximal (15-fold) within 6 h, and returned to baseline within 24 h of treatment, although maximal induction (10-fold) by RA (1 microM) did not occur until 24 h posttreatment. Induction of IL-8 by TPA was blocked by 1-(5-isoquinolinyl-sulfonyl)-2-methylpiperazine, which inhibits PKC and cAMP-dependent protein kinases (PKA), but not by N-(2-ganidinoethyl)-5-isoquinoline sulfonamide, which preferentially inhibits PKA, consistent with the participation of PKC in the induction of IL-8 by TPA. In contrast, induction of IL-8 by RA was inhibited by both 1-(5-isoquinoline sulfonamide and N-(2-gamidinoethyl)-5-isoquinoline sulfonamide, suggesting the participation of PKA in the induction of IL-8 by RA. However, activation of PKA by addition of cAMP analogues was not sufficient to induce IL-8 expression. Induction of IL-8 by RA also did not appear to be mediated indirectly through induction of IL-1, because addition of IL-1R antagonist did not block IL-8 induction by RA. RA and TPA added in combination synergistically enhanced expression of IL-8 mRNA, measured at 6 (2-fold) and 24 h (10-fold) posttreatment. To investigate the mechanism of this synergy, the effect of TPA and RA on fibroblast PKC activation and PKC isozyme levels were determined. TPA, either alone or together with RA, but not RA alone, stimulated phosphorylation of an endogenous 80-kDa PKC substrate. Dermal fibroblasts expressed three PKC isozymes (alpha, (delta, and (epsilon). TPA, but not RA, down-regulated PKC-alpha, neither TPA or RA affected the level of PKC-delta, and both TPA and RA down-regulated PKC-epsilon. This latter effect was enhanced 2-fold by addition of RA and TPA together. These data suggest that modulation of PKC-epsilon may be a common participant in the regulation of IL-8 expression by TPA and RA.

Monoclonal antibody (mAb) IL-A17 characterizes a subset of bovine T lymphocytes. IL-A17 recognizes a 34,000-35,000 MW doublet, designated BoT8, which is expressed on the surface of approximately 20% of peripheral blood mononuclear leucocytes (PBM), a subpopulation of lymphocytes in T-dependent areas of lymph nodes and spleen, and about 70% of thymocytes. This molecule is not expressed on B lymphocytes, monocytes/macrophages or granulocytes. Double labelling of PBM showed that the BoT8+ population is distinct from the T lymphocyte subset expressing BoT4. BoT8+ lymphocytes purified with a fluorescence-activated cell sorter (FACS) proliferated poorly in response to mitogenic and alloantigenic stimulation in the absence of exogenous growth factors. IL-A17 had no inhibitory effect on proliferation of PBM to mitogens (Con A and PHA) or alloantigens and no measurable effect on the in vitro generation of cytolytic effector cells. However, in some experiments IL-A17 was found to block partially allospecific cytolytic function mediated by bulk effector cell populations when included in 51Cr-release assays. Fractionation of effector cells generated in an allogeneic mixed leucocyte culture (MLC) demonstrated that cytotoxic cells specific for class I major histocompatibility complex (MHC) antigens reside within the BoT8+ population. Based on these data, and information reported elsewhere on alloreactive bovine T-cell clones, BoT8 is considered to be analogous to CD8 in humans and equivalent molecules in other species.