Effects of IL-4 on antigen-induced production of eosinophil chemotactic activity from human mononuclear leukocytes

The effect of IL-4 on antigen-induced production of eosinophil chemotactic factors (ECF) from human peripheral blood mononuclear cells (PBMC) was examined. Antigen-induced ECF production was enhanced in a dose-dependent manner when PBMC were pretreated with IL-4. The most potent enhancement was induced by IL-4 at a concentration of 30 U in tuberculin-sensitive PBMC, and 3 U in Dermatophagoides farinae (Df)-sensitive PBMC. A short period of pretreatment (30 min to a h) was sufficient for the enhancement, whereas a longer period of treatment was less effective. IL-4 pretreatment suppressed PPD-induced IFN gamma and IL-5 production but enhanced ECF production. Furthermore, we found that Df induced IL-5 but not IFN gamma production from PBMC, and that IL-5 production was not affected by pretreatment with IL-4. Next, experiments were done to clarify whether the ECF produced by PPD-stimulated PBMC was different from that produced by Df-stimulated PBMC. It was thus found that the pi of both ECF was at about pH 7.0 and that unlike chemokines such as RANTES and eotaxin, they had no affinity for heparin.