Bactericidal and Metabolic Properties of Human Eosinophils

The bactericidal and metabolic activities of peripheral leukocytes obtained by dextran sedimentation from six patients with eosinophilia (50%-90%) due to a variety of etiologies were compared to cells collected from normal donors (70%-95% polymorphonuclear leukocytes). Eosinophils exhibited less phagocytosis than granulocytes, which appeared to account for diminished bactericidal activity against S. albus, S. aureus, and E. coli. The oxidation of glucose-1-¹⁴C, glucose-6-¹⁴C, and formate-¹⁴C were all significantly greater by nonphagocytizing eosinophils than neutrophils. With phagocytosis the increase in glucose-1-¹⁴C and glucose-6-¹⁴C oxidation was greater for eosinophils than neutrophils despite less measurable particle ingestion. The oxidation of formate-¹⁴C by phagocytizing eosinophils was similar to neutrophils in two patients studied. Leukocytic pyrogen (LP) was produced by phagocytosis of heat-killed S. albus or exposure to endotoxin in four out of five cases studied. Blood cells obtained from the fifth patient who had a probable myeloproliferative disorder did not produce significant amounts of LP when similarly stimulated. The common feature of diminished phagocytic activity and elevated resting oxidative metabolism in all patients regardless of etiology of the eosinophilia suggest that this property is common to all eosinophils. The failure of the morphologically abnormal eosinophils of the last patient to release LP served as another distinguishing feature of his cells and may be common to myeloproliferative disorders of the granulocyte series in general.