Comparative Studies on Alveolar Macrophages and Polymorphonuclear Leukocytes

II. The Ability of Guinea Pig Alveolar Macrophages to Produce H₂O₂

Abstract

Guinea pig alveolar macrophages (A-M∅) were studied with respect to the phagocytic metabolism: the respiratory burst and its KCN sensitivity, the ability to generate H₂O₂, and myeloperoxidase (MPO) activity. Only fifty percent of the O₂ uptake by A-M∅ samples during phagocytosis was inhibited by the addition of 1mM KCN. Guinea pig A-M∅ released H₂O₂ amounting to 7.7 and 12.5 nmol/min/10⁷ cells upon addition of E. coli in the absence and presence of anti-E. coli antibody, respectively. Myristic acid, an effective membrane activator, induced a marked release of H₂O₂ amounting to 16.1 nmol/min/10⁷ cells. We observed a high MPO activity in some alveolar lavage cells which contained a large number of polymorphonuclear leukocytes (PMN), but none at all in preparations containing fewer PMN. The MPO activity detected did not seem to be due to A-M∅, but to the PMN contained in the preparations.