Interleukin 8-inhibitor and inducer of histamine and leukotriene release in human basophils.

We have shown previously that interleukin 8 (IL-8) induces histamine and leukotriene release in human basophils exposed to interleukin 3 (IL-3). We now found that pretreatment with low concentrations of IL-8 selectively inhibits this response. Inhibition was significant at 0.01 nM IL-8 and virtually complete at 1 nM, which is about 100-fold lower than the concentration required for induction of mediator release. IL-8 dependent responses were also inhibited, albeit to a lesser extent, by preincubation with neutrophil-activating peptide 2 (NAP-2), but not with connective tissue-activating peptide III (CTAP-III) or platelet factor 4 (PF4). Release induced by C5a, fMet-Leu-Phe, or anti-IgE antibody, by contrast, was not affected.