Sister-chromatid exchange induction by sodium selenite: dependence on the presence of red blood cells or red blood cell lysate.

Sodium selenite (Na2SeO3) sister-chromatid exchange (SCE) induction was studied in both short-term and long-term cell cultures. The ability of Na2SeO3 to induce SCEs was found to depend on the culture conditions employed. Concentrations of Na2SeO3 (7.90 X 10(-6) M and greater) that produced elevated SCE frequencies in whole blood cultures resulted in control level SCE frequencies (6-8 SCEs/cell) in Ficoll-Hypaque--purified lymphocyte cultures. However, whole blood and purified lymphocyte cultures were equally sensitive to SCE induction by methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), and N-hydroxy-2-acetylaminofluorene (N-OH-AAF). Analysis of different whole blood components showed that the presence of red blood cells (RBCs), and specifically RBC lysate, was a prerequisite for Na2SeO3 SCE induction in purified lymphocyte cultures. The SCE frequencies of xeroderma pigmentosum (XP12RO) and normal human lymphoblastoid cell lines were also found to be unaffected by Na2SeO3 concentrations that produced elevated SCE frequencies in whole blood cultures. Incubation of these latter two cell types with Na2SeO3 and RBC lysate resulted in SCE frequencies comparable to those in Na2SeO3-exposed whole blood cultures.