Oxygen-induced cytogenetic instability in normal human lymphocytes.

Chromosomal aberrations were scored in normal human lymphocytes cultured for 3 to 7 days at 20, 40, 50, and 60% oxygen. Compared to normoxic cultures (20% O2), in hyperoxic cultures (40% to 60% O2) the frequency of aberrant cells was significantly increased, especially at the longer incubation times. The increase was mainly due to chromatid-type damage: chromatid gaps, breaks, and interchanges. In addition, long-term hyperoxic cultures had a remarkably high incidence of endoreduplications, up to 7.4%. It appears that prolonged hyperoxic incubation induces a pattern of cytogenetic abnormalities in normal human lymphocytes similar to that present "spontaneously" in 3-day normoxic cultures from patients with Fanconi anemia.