Factors that affect the results of microcytotoxicity testing in man.

A great number of variables affect the pattern of test results obtained in studies of cell-mediated cytotoxicity of blood lymphocytes for tumor cells in vitro. The classic microcytotoxicity test measures both cell destruction and effects on cell growth. Microcytotoxicity tests in which isotopically prelabeled target cells are used measure primarily cell destruction. The method of preparation of effector cells from human blood can greatly influence results of such tests. Perhaps the most clear-cut example of this influence is the effect of Tris--NH4Cl treatment of effector cells to lyse contaminating red blood cells. This treatment inactivates the lytic function of certain effector cell types. In addition, a major consideration that must be kept in mind is the difference in patients under study by different groups of investigators.