The application of flow cytometry in the study of natural killer cell cytotoxicity

A flow cytometric assay was developed to detect the cytotoxic function of natural killer (NK) cells. This procedure employed a single fluorochrome and forward angle light scatter to differentiate dead cells from live cells. When results obtained by flow cytometry were compared with 51Cr release assay, this assay showed high specificity and sensitivity. When propidium iodide was used to stain target cells killed by NK cells, we found that NK cell cytotoxicity was not cell cycle specific.