Bleomycin increases superoxide production in the most active alveolar macrophage subpopulation

Pig alveolar macrophages were separated into three subpopulations by density centrifugation. The most dense subpopulation of macrophages had the greatest rate of superoxide anion production of 4.4 +/- 2.6 nmol/1 x 10(6) cells/min. Bleomycin had its greatest effect on this subpopulation by increasing the rate by nearly 100% in cells stimulated with phorbol myristate acetate or phorbol dibutyrate. Bleomycin increased the maximum rate of superoxide production without changing the apparent Km of 0.012 microgram/ml. Bleomycin did not quantitatively effect phorbol dibutyrate binding to alveolar macrophages. The cells have 9.1 +/- 1.0 x 10(5) sites/cell with a KD of 16 nmol. Results indicate that bleomycin may enhance superoxide production by effecting steps distal to protein kinase C in the superoxide anion production pathway.