Progressive increases in serum catalase activity in advancing human immunodeficiency virus infection

We found that serum from individuals with Acquired Immunodeficiency Syndrome (AIDS) had more (p < .05) catalase activity (31.5 ± 5.2 U/ml) than serum from healthy control subjects (7.3 ± 0.8 U/ml). Moreover, serum catalase (but not glutathione peroxidase) activity increased progressively with advancing human immunodeficiency virus (HIV) infection (i.e., AIDS > symptomatic infection > asymptomatic infection > controls). Increases in serum catalase activity correlated with increases in serum hydrogen peroxide (H₂O₂) scavenging ability and reached levels which decreased exogenous H₂O₂-mediated injury to cultured endothelial cells without altering neutrophil bactericidal activity or mononuclear cell cytotoxicity in vitro. Serum catalase activity correlated with serum lactate dehydrogenase (LDH) activity but did not appear to be a consequence of erythrocyte (RBC) hemolysis since RBC fragility and serum haptoglobin levels were comparable in HIV-infected and control subjects. Increases in serum catalase activity may reflect and/or compensate for systemic glutathione and other antioxidant deficiencies in HIV-infected individuals.