Cr-releasing cytotoxicity tests: study of parameters influencing their reliability.

Parameters which are of interest for the better performance of the Cr-releasing cytotoxicity tests were examined, such as type of cells used as targets; influence of various media on the viability of the cells, on uptake of radioactive chromium and on nonspecific chromium release; and influence of specific activity of chromium on the extent of labelling of the targets. The test has been applied to follow the course of primary and secondary immune responses to H-2 alloantigens.