Natural cytotoxic (NC) activity: A multi-lineage system regulated by IL-2

The studies described in this report demonstrate that NC activity is the function of a number of distinct effector cell populations and not due to a single type of NC cell. While IL-2 was found to augment the NC activity of all populations tested, in vitro culture and T-deficient mutant mouse studies would suggest that it is not necessary for maintaining NC activity. With NC being an ‘activity’ rather than the function of a single effector cell type, identifying all populations that lyse the WEHI-164 target as a single type of effector is no longer valid. As discussed previously, the same situation may apply to the NK compartment [43].