Cellular and Nuclear Toxicity of HgCl2 to In Vitro Grown Lymphocytes from Human Umbilical Cord Blood

Abstract

The present study examines the toxicity of HgCl2, using in vitro grown lymphocytes from human umbilical cord blood. Lymphocytes were diluted with Dulbecco’s modified Eagle’s medium, and were grown in the presence of grading doses of HgCl2. The cell-toxicity on grown lymphocytes was assessed using three staining procedures, trypan blue (TB) assay, acridine orange/ethidium bromide (AO/EB) staining and propidium iodide (PI) staining cytologically; and 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide (MTT) assay. The standard procedure was carried out for monitoring the live cell density. Additionally, the comet assay was done to ascertain levels of HgCl2 in inducing the nuclear disruption of lymphocytes. Mean results of three independent experiments are presented. Probit-computed lethal concentration (LC) values obtained were in ranges, 5.00–16.22 mg/l as LC25, 13.18–24.54 mg/l as LC50, and 25.12–34.67 mg/l HgCl2 as LC75, respectively at 24 h with incubation with HgCl2, using TB, AO/EB, PI staining procedures and the MTT assay. Experimentally, the minimum inhibitory concentration (MIC), the highest permissive concentration (HPC) and the LC100 values were in ranges, 5, 35–40 and 40–45 mg/l, respectively, for cytotoxicity. With comet assay data, the MIC value was 5 mg/l, whereas the HPC and LC100 values were 35 and 40 mg/l, respectively; and LC25, LC50 and LC75 values were 15.48, 20.41 and 28.84 mg/l HgCl2, respectively. Thus, HgCl2 levels higher than 5 mg/l and below 40–45 mg/l were toxic to in vitro cultured human lymphocytes.