FIG. 1.

O₂⁻ production by human granulocytes during incubation with Y. enterocolitica. Granulocytes were incubated together with various numbers of pYV⁻ Y. enterocolitica (○) or pYV⁺ Y. enterocolitica (■) organisms for 30 min. O₂⁻ production was determined by measuring the superoxide dismutase-inhibitable reduction of ferricytochrome c. The mean (± standard error) O₂⁻ production by granulocytes in the absence of bacteria amounted to 3.64 (±0.28) nmol of O₂⁻ per 10⁶ granulocytes per ml per 30 min and is indicated by the dashed line.