OXYGEN RADICAL PRODUCTION BY BLOOD EOSINOPHILS IS REDUCED DURING BIRCH POLLEN SEASON IN ALLERGIC PATIENTS

Background The eosinophil granulocyte takes part in allergic inflammat ory diseases, like asthma and rhinitis. The aim of this study was to i nvestigate the oxidative metabolism of the blood eosinophils and neutr ophils from birch pollen allergic patients, during and after exposure to their allergen. Methods Thirteen birch pollen allergic patients, wi th seasonal symptoms of rhinitis, with or without asthma, were followe d. The cells were purified using a percoll gradient and the MACS syste m. The eosinophil purity in all samples was >95%. The oxidative metabo lism of both the PMN and the eosinophils was measured by means of a ch emiluminescence (CL) assay, with luminol or lucigenin as the amplifier , and using PMA (16 nM) as the activator. Results In relative terms, t he lucigenin CL by the eosinophils was 5-10-fold higher than that of t he PMN, P = 0.002. The eosinophils of the birch pollen allergic patien ts produced less oxygen radicals during the season, compared to the re ference group, measured both with luminol CL and lucigenin CL, P = 0.0 1 and P = 0.02 respectively. Out of season, there was no difference. T here was also no difference, during either period, between patients an d references in PMN CL. Separating the eosinophils into hypodense and normodense fractions, showed a decreased oxidative metabolism by the h ydrodense eosinophils. Conclusion We conclude that the eosinophils of birch pollen allergic patients have reduced production of oxygen radic als when the patients are exposed to their allergen, which could depen d on higher amounts of hypodense eosinophils in the blood during seaso n.