Influence of conventional house-dust-mite immunotherapy on histamine releasability from the basophil

Shim, Jung Yeon; Kim, Bong Seong; Cho, Sang Heon; Min, Kyung Up; Hong, Soo Jong

Abstract

BACKGROUND
Allergen-specific immunotherapy has been shown to be clinically effective in the treatment of patients with atopic asthma, but the mechanisms are still unclear. Some of the immunologic changes include increase of an allergen-specific IgG antibody, decrease of allergen-specific IgE after transient increase, allergen-specific T-cell shift in cytokine expression from Th2 to Th1 cytokines, and decrease of basophil histamine releasability.
OBJECTIVE
To investigate the influence of immunotherapy on basophil releasability, we examined the changes of IgE-mediated and non-IgE-mediated basophil histamine releasability during immunotherapy.
METHODS
Fourteen Dermatophagoides farinae (D.f) sensitive asthmatic children with conventional immunotherapy were investigated. Basophil histamine releasability was measured prior to immunotherapy and 4 and 9 months after immunotherapy. Basophils were stimulated with D.f and goat antihuman IgE antibody as IgE-mediated stimuli which act on IgE-receptor, and formyl-Met-Leu-Phe (fMLP) as non-IgE-mediated stimuli which acts on non-IgE receptor, and calcium ionophore A23187 as non-IgE-mediated stimuli which does not act on cell surface receptors. Histamine was measured by automated fluorometric technique.
RESULTS
Before immunotherapy, there were significant correlations between histamine release by D.f and histamine release by fMLP, and between histamine release by D.f and histamine release by anti-IgE antibody, but no correlation between histamine release by D.f and histamine release by calcium ionophore. Histamine release by D.f and by anti-IgE antibody decreased at and 9 months after immunotherapy compared to those before immunotherapy. Histamine release by fMLP and by calcium ionophore showed no significant changes after immunotherapy. There was no significant change of total histamine release after immunotherapy.
CONCLUSION
Conventional immunotherapy has influenced only the IgE-mediated basophil releasability. IgE-mediated and non-IgE-receptor-mediated basophil releasability was correlated before immunotherapy, but only IgE-receptor-mediated basophil releasability decreased after immunotherapy. These findings suggest that a kind of physicochemical change may happen on the IgE receptors of basophil, which may induce decrease of IgE-mediated basophil histamine releasability after immunotherpy.