Exogenous IL-8 induces phagocyte activation in the compound ascidian Botryllus schlosseri.

We studied the responses of Botryllus schlosseri phagocyte to human recombinant IL-8 (hrIL-8) at three different concentrations (10, 25 and 50 ng/ml). Both spreading ability and phagocytosis were significantly enhanced by the exogenous chemokine at 25 and 50 ng/ml in the culture medium and the effects are coupled to modifications of the actin cytoskeleton. The addition of the signal transduction inhibitors suramin, calphostin C and H-89 to the incubation medium, inhibits the above-reported effects and suggests that exogenous IL-8 acts via protein kinase (PK) C and PKA pathways through its binding to a G protein-coupled receptor.