An easy quantitative cytotoxicity assay using a Coulter Counter.

A rapid and reproducible cytotoxicity assay using an electronic particle counter, such as a Coulter Counter, is described. With anti-BAtheta antiserum and mouse thymocytes as target cells, comparable, but more objective results than those by the ordinary dye exclusion method were obtained in a short time. The procedure is very simple: Cells in a plastic multi-well plate are first exposed to antibody and complement or other cytolytic conditions and then Pronase E is added to each well to digest dead cells completely. Then the nuclei of remaining viable cells are liberated from the cytoplasm and cell debris by solubilization with Zap-Oglobin and counted in the counter. Under these conditions, contaminating erythrocytes do not cause interference, because they are completely solubilized with Zap-Oglobin. This technique should be useful for measurements on numerous samples, such as in monitoring chromatograms of cytotoxic activity and titrating antibody and complement.