Effects of temperature on chemically induced sister-chromatid exchange in human lymphocytes

Abstract

Lymphocytes from healthy adults were studied for sister-chromatid exchanges (SCEs) when pulse-treated in G 0 with mitomycin C (MMC), ethyl methanesulfonate (EMS), or 4-nitroquinoline N-oxide (4NQO) at various temperatures ranging from 0°C to 41°C and then cultured in medium containing 5-bromodeoxyuridine at 37°C. The results showed that the frequencies of SCEs induced by MMC or EMS varied according to the treatment temperature. In MMC- or EMS-exposed cultures, the SCE frequency increased continuously with increasing treatment temperature; treatment at 37°C resulted in a 3–4 times greater induction of SCEs than did that at room temperature (25°C). On the other hand, SCE frequencies in cells exposed to 4NQO remained within normal deviation, showing no temperature-dependent changes. Baseline SCE frequencies remained almost constant within the temperature range tested. These data indicate that treatment temperature is a very critical factor in determining the sensitivity of cells to the chemical induction of SCEs.