Superoxide dismutase in polymorphonuclear leukocytes of term newborn infants and very low birth weight infants.

We investigated the activity and the content of copper and zinc-containing superoxide dismutase (SOD) and superoxide anion (O2-) production in polymorphonuclear leukocytes (PMN) from healthy term newborn infants, very low birth wt infants, and healthy adults. SOD activity in PMN was measured with nitroblue tetrazolium reduction assay on PAGE, and the SOD content in PMN was determined with an ELISA using a monoclonal antibody against human copper and zinc-containing SOD. The activity and the content of SOD in the term neonatal PMN and VLBW-infants' PMN were significantly lower than those in the adults' PMN (term newborn infants, 6.6 +/- 0.6 U/mg protein and 170.4 +/- 16.3 ng/mg protein, n = 10; VLBW infants, 6.8 +/- 0.9 and 173.0 +/- 16.2, n = 6; adults, 10.3 +/- 0.6 and 241.9 +/- 13.3, n = 10; values were expressed as mean +/- SEM). Both the phorbol myristate acetate- and the N-formyl-methionyl-leucyl-phenylalanine-induced O2- production rates of VLBW-infants' PMN were significantly higher than those of the term neonatal PMN. The phorbol myristate acetate-induced O2- production rate of the term neonatal PMN was significantly lower than that of the adults' PMN. The phorbol myristate acetate-induced H2O2 production rate of the term neonatal PMN was significantly lower than that of the adults' PMN. The conversion rate from O2- to H2O2 of the neonatal PMN was similar to that of the adults' PMN.(ABSTRACT TRUNCATED AT 250 WORDS)