Respiratory Burst of Normal Human Eosinophils

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Abstract
Oxidative metabolism of eosinophils has generally been studied in cells from patients with eosinophilia. We isolated eosinophils with purity of >95% from normal donors. Oxygen metabolism of eosinophils and neutrophils was compared using O2 production as a measure of the stimulus-induced respiratory burst. During 10 min of stimulation, using phorbol myristate acetate (PMA) or opsonized zymosan (OPZ), eosinophils produced two to three times as much O2 as did neutrophils. Continuous kinetic analysis was used to measure the latency period and maximal rate of O2 production. Eosinophils had a shorter latency period and greater rate of O2 production than did neutrophils at all concentrations of PMA. With OPZ stimulation, O2 production rates by both cells were similar. The latency periods were similar with high concentrations of OPZ but at limiting amounts of OPZ eosinophils had a longer latency period than did neutrophils. In addition, the kinetic assay demonstrated that the respiratory burst in eosinophils was more sustained than in neutrophils. These results indicate substantial differences in the oxidative burst of eosinophils and neutrophils with respect to activation, capacity, and regulation. These distinctive features of O2 production by eosinophils may be important in host defense against metazoan parasites or in tissue injury during inflammation.