A modified short-term cytotoxicity test: assessment of natural cell-mediated cytotoxicity in whole blood

Using whole blood from normal subjects, we have observed natural killing of K562 cells in a 4 h 51Cr-release assay comparable with that shown by separated PBMC and whole blood depleted of serum components. Separated plasma was not toxic towards K562 targets, and failed to potentiate the level of PBMC cytotoxicity through ADCC. The presence of red blood cells did not influence natural killing. The natural cytotoxicity of whole blood was augmented by interferon and depressed by prostaglandins E1 and E2. Studies with appropriate control blood fractions show that cytotoxicity tests with whole blood provide results reflecting natural cell-mediated cytotoxicity.