The effect of human alpha leukocyte interferon (IFN) on the frequency of sister chromatid exchanges (SCE) in the KB cell line.

Concentrations of 50, 500 and 5,000 iu/ml of natural human alpha leukocyte interferon (IFN) were added into the culture medium of KB cells, 4 h after serial passage, in the presence of 5-bromo-desoxyuridine (Brdu) at 10 micrograms/ml. Similar cultures without IFN were set up as controls. After 72 h of incubation, the harlequin technique (differential staining of sister chromatids) was applied in order to discriminate among the metaphases of different generations and to appreciate the frequency of sister chromatid exchanges (SCE) in the second generation cells. The incidence of sister chromatid exchanges was slightly increased following IFN treatment but no dose-effect relationships were observed. At the same time, cell cycle kinetics estimated as replication index (RI) and average generation time (AGT) was not modified in IFN-treated cells as against the controls.