Superoxide dismutase and the resistance of Escherichia coli to phagocytic killing by human neutrophils.

Transformation of Escherichia coli K-12-derived strains with a plasmid carrying the genetic determinants for synthesis of lipopolysaccharide O antigen by Shigella dysenteriae allows the construction of phenotypically smooth derivatives. We show that such E. coli K-12 derivatives are highly resistant to killing by human serum. Isogenic wild-type and sodB mutant (Fe superoxide dismutase-deficient) strains were constructed. The results of experiments on phagocytic killing of these strains by human neutrophils are reported. We observed no difference between the sensitivities of wild-type and sodB mutant strains to phagocytic killing, in contrast to the results reported by other researchers who used species other than E. coli or strains other than K-12.