Metabolic reduction of chromium by alveolar macrophages and its relationships to cigarette smoke.
Pulmonary alveolar macrophages (PAM), obtained by bronchoalveolar lavage from 47 individuals, reduced hexavalent chromium [Cr(VI)] and decreased its mutagenicity. Their specific activity--mostly mediated by cytosolic, enzyme-catalyzed mechanisms--was significantly higher than in corresponding preparations of mixed-cell populations from human peripheral lung parenchyma or bronchial tree, or from rat lung or liver. At equivalent number of PAM, Cr(VI) reduction, total protein, and some oxidoreductase activities were significantly increased in smokers. No appreciable variation could be detected between lung cancer and noncancer patients. In rats, the Cr(VI)-reducing activity of PAM preparations was induced by Aroclor 1254. Thus, alveolar macrophages provide crucial defense mechanisms not only by phagocytizing metals, but also by metabolically reducing Cr(VI). The epithelial-lining fluid (ELF) also displayed some Cr(VI) reduction. Together with already investigated metabolic processes occurring inside lung cells, these mechanisms are expected to determine thresholds in the pulmonary carcinogenicity of chromium.
F L
FL
Petrilli
G A
GA
Rossi
A
A
Camoirano
M
M
Romano
D
D
Serra
C
C
Bennicelli
A
A
De Flora
S
S
De Flora
D000818:Animals; D001140:Aroclors / Q000494:pharmacology; D020111:Chlorodiphenyl (54% Chlorine); D002857:Chromium / Q000378:metabolism*; D001728:Dicumarol / Q000494:pharmacology; D008058:Dihydrolipoamide Dehydrogenase / Q000032:analysis; D005954:Glucosephosphate Dehydrogenase / Q000032:analysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D009152:Mutagenicity Tests; D009252:NADPH Dehydrogenase / Q000032:analysis; D010734:Phosphogluconate Dehydrogenase / Q000032:analysis; D011650:Pulmonary Alveoli / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012907:Smoking; D013997:Time Factors
D001140:Aroclors; D002857:Chromium; D020111:Chlorodiphenyl (54% Chlorine); D001728:Dicumarol; D010734:Phosphogluconate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D009252:NADPH Dehydrogenase; D008058:Dihydrolipoamide Dehydrogenase