Comparative Studies on Alveolar Macrophages and Polymorphonuclear Leukocytes

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Abstract
The oxidative metabolism of rabbit alveolar macrophages (A-MØ) was compared with that of rabbit polymorphonuclear leukocytes (PMN) with respect to H2O2 generation by intact cells or subcellular fractions. Rabbit PMN exhibited an increase in the oxygen uptake and a marked release of H2O2 upon addition of heat-killed E. coli in the presence and absence of opsonin. However, rabbit A-MØ exhibited an increase in the oxygen uptake upon addition of E. coli only in the presence of anti-E. coli serum as an opsonin, whereas a very small amount of H2O2, release was observed during ingestion of the opsonized E. coli. The generation of O2− and H2O2 by a granule-rich fraction isolated from phagocytosing PMN was larger than that by a similar fraction isolated from resting PMN. However, there was no significant difference in O2− and H2O2 generation by the granule fractions between phagocytosing and resting A-MØ in the presence of either NADH or NADPH. In contrast to the granule fraction of rabbit PMN, the O2− and H2 O2 generating activities in the A-MØ granule fraction were higher in the presence of NADH than in the presence of NADPH. The rates of NADH and NADPH oxidation by both A-MØ and PMN granule fractions were measured with and without addition of Mn2+ to the assay medium. The effect of Mn2+ on the NAD(P)H oxidase was found to differ between rabbit A-MØ and PMN.