Human K cell activity. I. Relation to effector cells buoyant density.

In order to disclose a relation between human K cell activity and effector cells buoyant density, this activity was tested, against antibody sensitized 51Cr labelled L1210 cells, in lymphocytes subsets obtained by centrifugation to equilibrium in discontinuous bovine serum albumin gradients. Since K cell activity is mainly present in null and T cells, this study focused on the buoyant density subsets of human T and null cells. Our results show that, in these T and null cells, K cell activity is directly related to cell density, the less dense fraction having the highest cytotoxic capacity. From the recovery of Lytic Units, it is shown that the K cell pool can be associated with the population of activated or precursor cells in human peripheral blood.