A micro-version of the 51Cr release assay for cytotoxic lymphocytes

A micro-version of the 51Cr release assay for cytotoxic lymphocytes has been devised, which is conducted in Terasaki plates, in a total reaction volume of 8 microliter. The conditions necessary to make the microassay equivalent in sensitivity and reproducibility to the standard macroassay are described. In comparison with the standard macroassay, the microassay provides a 10-fold reduction in the number of effector cells employed and represents a 50-fold reduction in reaction volume. The assay has been particularly valuable in the saving of antisera when these are employed to block target cell lysis, or to selectively inactivate cells of a particular phenotype in the effector cell population.