A lectin‐binding soluble factor released by CD8+CD57+ lymphocytes from AIDS patients inhibits T cell cytotoxicity

Abstract

CD8⁺CD57⁺ T cells, expanded in peripheral blood lymphocytes of AIDS patients, inhibit the effector phase of HLA‐specific cytotoxic T lymphocytes, natural killer and lymphocyte‐activated killer cells in a 4‐h chromium‐release assay. This inhibitory activity present in supernatants of purified sorted CD8⁺CD57⁺ cells is mediated by a non‐antigen‐specific inhibitory factor which is distinct from prostaglandin E₂, T cell growth factor (TGF)‐β, latent‐TGF‐β, tumor necrosis factor (TNF)‐α and TNF‐β. Partial biochemical characterization demonstrates that the CD8⁺CD57⁺ inhibitory activity (a) is heat, trypsin and acid resistant, (b) binds to concanavalin A columns, indicating its glycosylation state and (c) is mediated by a 20–30‐kDa soluble molecule.