Influence of bronchial allergen challenge on histamine release by human basophils

Background Basophils can be primed by cytokines such as interleukin (IL) -3 , IL-5 or granulocyte macrophage-colony stimulating factor (GM-CSF). It has been described that the concentrations of these cytokines are enhanced at sites of allergic inflammation as well as systemic in allergic asthma. Objective To investigate the priming status of basophils as detected by tha psigargin-induced histamine release during bronchial allergen challenge. Methods Ten subjects allergic to house dust mite were challenged via an aer osol delivery system. Spontaneous leucocyte histamine release as well as hi stamine release induced by various stimuli was measured in vitro at several time points. In addition, lung function parameters, serum IL-5 and blood e osinophil counts were evaluated. Results We found no effect of bronchial allergen challenge upon spontaneous leucocyte histamine release, nor upon histamine release induced by anti-im munoglobulin (Ig) E, house dust mite extract, C5a, fMLP, IL-3, PMA+ thapsig argin or IL-3+ thapsigargin. However, the priming status of basophils as me asured by thapsigargin-induced histamine release was enhanced at 24 h after bronchial allergen challenge. Analysis of the individual data showed a het erogeneous initial response (30 min, 6 h) followed by a predominant increas e at 24 h after allergen challenge. This increase in the thapsigargin-induc ed histamine release correlated with the increase in serum IL-5 levels at 2 4 h after allergen challenge. Conclusion The priming status of human basophils as measured by thapsigargi n-induced histamine release is enhanced 24 h after allergen challenge.