Fc receptors on human T lymphocytes: II. Cytotoxic capabilities of human Tγ, Tμ, B, and L cells

Abstract

Subpopulations of human peripheral blood lymphocytes were prepared by rosetting techniques employing neuraminidase-treated sheep erythrocytes (SRBC n), sheep erythrocytes coated with IgM and murine complement (EAC′), and bovine erythrocytes coated with IgG and IgM. The isolated subpopulations were tested in assays of natural cytotoxicity (NC), antibody-dependent cellular cytotoxicity (ADCC), and mitogen-induced cellular cytotoxicity (MICC). B cells (SRBC n−, EAC′+) did not mediate cytotoxicity. L cells (SRBC n−, EAC′−) mediated NC and ADCC but not MICC. T cells (SRBC n+) mediated NC, ADCC, and MICC. Separation of T cells into Fc-IgG (Tγ) and Fc-IgM (Tμ) subsets revealed that Tγ cells mediated NC, ADCC, and MICC while Tμ cells mediated only MICC. Thus MICC but not NC or ADCC was solely T-cell mediated. Tγ and L cells were functionally distinguishable in that Tγ cells but not L cells mediated MICC. Tγ cells and Tμ cells differed with regard to NC and ADCC effector function while both subsets mediated MICC.