Abstract
The aim of this study was to evaluate whether Na+ exerts its inhibitory effect on basophil histamine release induced by immunoglobulin E (IgE)-dependent (anti-IgE) and IgE-independent (N-formyl-methionyl-leucyl-phenylalanine (FMLP), interleukin-3 (IL-3)) stimuli in patients with allergic rhinitis (n = 24) and allergic bronchial asthma (n = 10). Peripheral blood leucocytes were stimulated with anti-IgE, FMLP and IL-3 in the presence of high and low Na+ concentrations, and histamine release was measured using a fluorometric method. In standard Na(+)-containing medium, spontaneous and stimulated histamine release was higher in allergic patients (n = 34) (both rhinitic and asthmatic) than in healthy subjects (n = 41). Na+ removal from extracellular medium and its isosmotic substitution with choline chloride or with N-methyl-D-glucamine led to a significant increase of anti-IgE-, FMLP- and IL-3-induced histamine release in normal subjects, but not in allergic patients. The increase in Na+ concentration in the extra-cellular medium was accompanied by a dose-dependent decrease of anti-IgE- and FMLP-induced histamine release in normal subjects, but not in allergic patients. The behaviour of atopics and healthy subjects was different and not related to the basophil responsiveness to activating signals. The incubation of basophils from healthy subjects with sera from allergic patients did not have a significant influence on the inhibitory effect of Na+. Basophils from healthy subjects and atopic patients respond differently when stimulated in a low Na+ medium. The reduced sensitivity to the inhibitory effect of Na+ may contribute to basophil dysfunction in patients with respiratory allergy.
