Population distributions of natural killer and K562 target cell conjugates

We studied the types of conjugates formed at different effector-to-target ratios (R) in the NK-K562 target system. Using purified natural killer (NK) effector cells prepared by a panning technique (greater than 98% CD16), distributions of conjugates are formed such that LTn (one NK cell bound to one or more target cells) are more common at R values less than 1, and LmT (one or more NK cells bound to one target cell) are observed at R greater than 1. Population distributions of these types of conjugates are in agreement with the predictions of the model previously reported for CTL target cell conjugates. In contrast, monocyte-depleted peripheral blood lymphocytes form conjugates in which the LT type is the predominant subpopulation for all values of R. The impact of cell purity on the kinetics and dynamics of cell-mediated cytotoxicity at the population level is discussed.