ASSESSMENT OF METAL EXTRACT TOXICITY ON HUMAN-LYMPHOCYTES CULTURED IN-VITRO

In this study the toxic effects of chromium, nickel, and cobalt extrac ts on in vitro cultured lymphocytes were evaluated. Graphite furnace a tomic absorption spectrometry was used to measure the ion concentratio n. After serial dilution of the extracts, the viability of lymphocytes at 24, 48, and 72 h was estimated by flow cytometry, including propid ium iodide staining and light scatter property assessment, and by MTT reduction test. The results of the investigation allowed us to conclud e that 1) standardization of the procedure for preparing extracts is f undamental to obtaining repeatability of results; 2) the toxicity of a n extract cannot be evaluated with a single viability assay; a combina tion of functional and structural tests is required; 3) when methods b ased on enzymatic reactions are performed, e.g. MTT test, it is advisa ble to replace the extract containing metal ions with fresh medium in order to avoid any interference with viability testing; 4) the amount of Co and Ni in the extract is similar, but the Cr release is very poo r; 5) the lower toxicity of Cr extract probably is due to the lower io n concentration; 6) the assessment of 50% cytotoxic concentration (TC5 0) allows quantification of materials toxicity and comparison of vario us metals; and 7) the determination of a noncytotoxic concentration, i .e., a concentration lower than TC10, is required for subsequent inves tigation of cell functions because such studies can be carried out onl y on viable cell population. (C) 1996 John Wiley & Sons, Inc.