The cytochrome b-558 molecules involved in the fibroblast and polymorphonuclear leucocyte superoxide-generating NADPH oxidase systems are structurally and genetically distinct.
We have demonstrated that human fibroblasts can release O2-. radicals by an NADPH oxidase system that appears to be functionally similar to the phagocytic system. Further analysis of these systems, however, with respect to the low-potential b-type cytochromes involved suggests that these two O2-.-generating systems are not structurally identical. Immunoblot analysis of fibroblast membranes with six different antibodies directed against both subunits of human neutrophil cytochrome b-558 indicated that the b-type cytochrome molecules involved in these systems were not identical. None of these anti-(neutrophil cytochrome b) antibodies recognized a similar cytochrome in fibroblast membranes, suggesting that the two cytochrome species are immunologically distinct. In addition, fibroblasts obtained from a patient suffering from X-linked chronic granulomatous disease (CGD) had a normal cytochrome b-558 content compared with control fibroblast membranes, whereas the cytochrome b-558 concentration in polymorphonuclear leucocytes (PMNs) from this patient was decreased to 10% of that found in PMNs from healthy controls. Likewise, the stimulated O2-. release in PMNs from this patient was less than 10% of that in control PMNs, whereas the fibroblasts showed stimulated O2-.-release rates that were indistinguishable from those of fibroblasts obtained from healthy persons. Since the genetic mutation responsible for this type of CGD results in the absence of cytochrome b-558 in PMNs, fibroblasts should be affected in the same way if both cytochrome species were identical. These results suggest therefore that the low-potential b-type cytochromes in PMNs and fibroblasts are structurally and genetically distinct.
Meier
B
B
Chemisches Institute, Tierärztliche Hochschule, Hannover, Germany.
Jesaitis
A J
AJ
Emmendörffer
A
A
Roesler
J
J
Quinn
M T
MT
D000906:Antibodies; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003573:Cytochrome b Group / Q000235:genetics* / Q000302:isolation & purification; D000939:Epitopes / Q000032:analysis; D005199:Fanconi Anemia / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D019255:NADPH Oxidases; D009504:Neutrophils / Q000201:enzymology*; D013481:Superoxides / Q000097:blood
D000906:Antibodies; D003573:Cytochrome b Group; D000939:Epitopes; D046911:Macromolecular Substances; D013481:Superoxides; C036888:cytochrome b558; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C022709:superoxide-forming enzyme