Selective induction of manganous superoxide dismutase in human monocytes

Radioimmunoassays for both human copper-zinc and manganous superoxide dismutases (Cu-Zn SOD and Mn SOD, respectively) have been developed, validated, and utilized to measure the concentrations of these enzymes in cultured monocytes. Monocyte Mn SOD increased 4.7-fold over basal during 3 days of culture, an increase that was markedly enhanced by stimulation with bacterial lipopolysaccharide (LPS). Cu-Zn SOD showed a transient decrease over the culture period but was unaffected by LPS. Stimulation with muramyl dipeptide had minimal effect on Mn SOD and no effect on Cu-Zn SOD during culture, even at a concentration capable of activating the monocytes, as defined by zymosan-induced superoxide production.