Studies of skin toxicity in vitro: dose-response studies on JB6 cells

There are many reasons for developing in vitro tests of toxicity including cost, speed, studies of mechanisms, and studies utilizing human cells and tissues. The present study focuses on the development of in vitro tests to predict in vivo toxicity by comparing them to data from the literature. A broad spectrum of model toxic compounds was evaluated for toxicity on mouse skin JB6 cells in culture. These included mercuric chloride, sodium lauryl sulfate, formaldehyde, dimethyl sulfoxide, benzoyl peroxide, and ionomycin, all of which have been proven to be positive in the Draize test or in cutaneous toxicity studies. Cell viability was evaluated every 15 min for up to 1 hr, and then after 24 hr of treatment using the Trypan Blue exclusion method; morphological changes were evaluated using phase-contrast and transmission electron microscopy. Dose- and time-dependent cell death and morphological changes were observed at concentrations ranging from 10(-14) to 10(-2) M. Arbitrary rankings were assigned based on 1) IC50 value estimated from the present data, and 2) in vivo toxicity reported in the Registry of Toxic Effects of Chemical Substances. Good correlation between in vitro and in vivo toxicity based on arbitrary rankings was observed. Thus, these findings suggest that the JB6 cell culture model can be used for predicting in vivo toxicity. In the future, it may be possible to utilize this system for the study of intracellular ionized calcium ([Ca2+]i), and the expression of oncogenes as early indicators of toxicity.