Effect of dialysable leukocytes extracts on antibody-dependent cellular cytotoxicity and lymphocyte Fc receptors.

Dialysable leukocyte extracts significantly inhibited the antibody-dependent cell-mediated cytotoxicity of normal human peripheral blood lymphocytes in both xenogeneic and allogenic assays. The inhibitory effect was dose-dependent. Fractions of dialysable leukocyte extracts separated on Sephadex G-25 column differed in their capacity to suppress cytotoxicity. Dialysable leukocyte extracts did not block EA-rosetting but inhibited the resynthesis of Fc receptors. Some explanations for the observed suppressive effect are discussed.