Superoxide anion production by neutrophils in myelodysplastic syndromes (preleukemia).

Superoxide anion (O2-) production by neutrophils from 14 untreated patients with acute nonlymphocytic leukemia (ANLL) was significantly less than that of healthy controls (4.93 +/- 1.99 vx 6.20 +/- 1.53 nmol/min/10(6) neutrophils, p less than 0.05). In 10 patients with myelodysplastic syndrome (MDS), however, it was not significantly different from the control level although 6 of the 10 patients had low levels, when individual patients were compared with the lower limit of the control range. An inverse correlation between the O2- production of neutrophils and the percentage of leukemic cells in the marrow existed in ANLL (r = -0.55, p less than 0.01), but not in MDS. Three of 4 MDS patients who died of pneumonia prior to leukemic conversion showed a low level of O2- production. The impaired O2- production by neutrophils from some MDS patients, probably due to the faulty differentiation from leukemic clones, may be one of the causes of enhanced susceptibility to infection.