EFFECT OF IN VITRO CYCLOSPORIN A TREATMENT ON HUMAN NATURAL AND ANTIBODY-DEPENDENT CELL-MEDIATED CYTOTOXICITY

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Abstract
Concentrations of 0.1-10.0 .mu.g/ml cyclosporin A (Cy A) do not directly inhibit the lysis of 51Cr-labeled K-562 [human leukemia] target cells by human peripheral blood natural killer (NK) cells nor of antibody-coated chicken red blood cells by antibody-dependent cellular cytotoxicity (ADCC) effector cells. Pretreatment of effector cells with Cy A for 18 h still failed to affect NK or ADCC effector function. Induction of NK cell activity by overnight pretreatment of effector cells by polyinosinate-polycytidylate (PolyIC) was inhibited by as little as 1 .mu.g Cy A/ml. The mechanism of inhibition may involve as direct effect of Cy A on induced or activated NK cells or inhibition of the release of Poly IC-induced interferon from lymphocytes.