Effect of bronchial allergen challenge on in vitro cytokine release by peripheral blood mononuclear cells of atopic patients

Background During the pollen season, peripheral blood mononuclear cells (PBMC) from allergic patients produce increased levels of Th2 cytokines after stimulation with allergen in vitro. We have studied the effect of a single bronchial provocation test (BPT) of allergic patients to determine whether allergen challenge in vivo modulates cytokine production by PBMC, after subsequent stimulation with the same allergen in vitro. Methods Twelve atopic asthmatic patients were challenged with the relevant allergen, and their PBMC, isolated before (TO) or 6 (T6) or 24 h (T24) after BPT, respectively, were cultured for 120 h in the presence or absence of the same allergen, after which cytokine production was measured by ELISA. Results Allergen-specific activation of the PBMC at TO resulted in interleukin (IL)-5 and IL-13 production, but not in detectable levels of interferon-gamma and IL-4. BPT did not induce the secretion of the latter cytokines. However, IL-5 and lL-13 production was significantly decreased at T24, as compared to TO. No statistically significant differences were found between the production of IL-10 before and after BPT. Conclusions In contrast to the effects of natural challenge with allergen, a decrease in the production of some Th2 cytokines by peripheral blood T cells was observed 24 h after BPT, suggesting a concomitant decrease in the frequency of allergen-specific T cells in the circulation.