Analytical subcellular fractionation of rabbit alveolar macrophages with particular reference to the subcellular localisation of pyridine nucleotide-dependent superoxide-generating systems and superoxide dismutase.

Normal and Bacillus Calmette-Guerin (BCG) vaccine-induced rabbit alveolar macrophage homogenates were fractionated by isopycnic density gradient centrifugation. Superoxide dismutase-inhibitable NAD(P)H-dependent nitro-blue tetrazolium reductase was found localised to endoplasmic reticulum and mitochondria. The normal macrophages tended to contain more of this activity than the BCG-induced macrophages. Two superoxide dismutases were found: cyanide-sensitive superoxide dismutase was predominantly present in the cytosol, with a small proportion in mitochondria; cyanide-resistant superoxide dismutase was found confined to mitochondria. Neither differed in specific activity betw-en the normal and BCG-induced macrophages.