Cytochrome b-245 in human alveolar macrophages

To kill microorganisms, phagocytes exhibit an oxidative burst with, in particular, a NADPH-dependent, superoxide-generating system that consists, in polymorphonuclear leukocytes (PMN), of a flavin enzyme and cytochrome b-245 (cyt b-245). We investigated the existence of this cytochrome in human alveolar macrophages (AM) because its presence would support its wide-spread occurrence in phagocytes and would raise the possibility of similarities in the oxygen-dependent killing mechanisms in AM and PMN. Moreover, we compared the amount of cyt b-245 in AM from patients with lung disorders with that from healthy subjects, by a differential spectroscopic measurement of its 558 to 559 nm characteristic band. This spectrum showed that cyt b-245 was present in AM. In AM of healthy subjects, the amount was similar to that found in PMN of blood. In AM of patients with miscellaneous lung diseases and in Am of infected lungs, the data were not modified.