Hydrogen peroxide release from eosinophils: Quantitative, comparative studies of human and guinea pig eosinophils

Abstract

Eosinophils play an important role in host defense against parasitic infection, employing both oxidative and nonoxidative systems to effect damage. The active oxygen product, hydrogen peroxide, either alone or in combination with the enzyme eosinophil peroxidase, may damage parasites. These studies use a sensitive fluorometric assay to document the release of hydrogen peroxide from guinea pig peritoneal exudate eosinophils and human peripheral blood eosinophils. Guinea pig eosinophils released 0.13 ± 0.02 (n = 10) nmol H2O2/105 eos/5 min under resting conditions which were markedly increased when stimulated by phorbal myristate acetate (PMA, 1 μg/ml) [4.80 ± 0.50 (19) nmol H2O2/105 eos/5 min], preopsonized zymosan [2.40 ± 0.17 (4) nmol H2O2/105 eos/5 min], or latex beads [1.14 ± 0.26 (5) nmol H2O2/105 eos/5 min]. Normal human peripheral blood eosinophils had greater resting release of hydrogen peroxide [0.34 ± 0.05 (8) nmol/ H2O2/105 eos/5 min], but were less effectively stimulated by PMA [3.12 ± 0.57 (9) nmol H2O2/105 eos/5 min], preopsonized zymosan [0.78 ± 0.16 (8) nmol H2O2/105 eos/5 min] or latex beads [0.69 ± 0.32 (6) nmol H2O2/105 eos] (p ≤ 0.05). Hydrogen peroxide release was markedly enhanced by the presence of exogenous glucose and was linearly dependent upon cell number when the soluble stimulus PMA was used. Particle-stimulated hydrogen peroxide was not necessarily enhanced by increases in the particle:cell ratio. The demonstration of the release of large amounts of hydrogen peroxide from eosinophils is further support for the concept that eosinophils play an active role in host defense.