A microcytotoxicity assay using 51Cr for measuring specific cell-mediated and humoral immune responses.

A microcytotoxicity assay (MCA) for measuring in vitro cell-mediated cytotoxicity (CMC) and humoral cytotoxicity which uses 51Cr-labelled target cells is described. Data is presented to show the uptake and rentention of 51Cr by various viable cultured cells. The CMC determined by 51Cr-labelled target cell retention in microtest II plate wells was verified by microscopic observation. Comparisons between the CMC observed 24 and 48 h after incubation of immune and normal lymphoid cells with 51Cr-labelled target cells were made. The factors, including savings in time and expense, which may make this modified MCA superior to other MCAs in use, are discussed.