An analysis of 51Cr-release data from cell-mediated cytotoxicity assays, plotted in the form of effector cell dilution curves, is analyzed in detail in terms of a saturation kinetics model for effector-target interaction. The effect of nonimmune (bystander) cells in the effector population is particularly examined. The theoretical development of the saturation model predicts that, at low concentrations of target cells, increasing proportions of bystander cells should broaden the range of effector cell concentration required to achieve a given increment of target cell lysis, but that at high target cell concentration this effect should disappear. Experimental validation of this prediction is presented.


This work was supported by United States Public Health Service Research Grant HD-06071, and a grant from the California Institute for Cancer Research.

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