Lysis of Human Immunodeficiency Virus Type 1 Antigen-Expressing Cells by CD4 and CD8 T Cells Ex Vivo

The aim of this study was to investigate the extent of lysis mediated by cytotoxic T lymphocytes (CTL) directed against human immunodeficiency virus (HIV) type 1 gag protein and envelope glycoprotein in peripheral blood mononuclear cells (PBMC) from HIV-1-infected subjects and to compare it with nonspecific envelope glycoprotein-directed cytotoxicity involving CD4 T cells. Most seropositive subjects exhibited antigen-specific cytotoxicity directed at one or both viral antigens in unstimulated or in vitro-stimulated PBMC (or both) mediated by CD8 T cells. In addition, all donors, including seronegative control persons, exhibited nonspecific calcium-independent cytotoxicity involving CD4 T cells and envelope glycoprotein-expressing cells. No calcium-dependent, antigen-specific CD4 T cell-mediated cytolysis was detected. In seropositive subjects, the vigor of nonspecific cytotoxicity was comparable to lysis by antigen-specific CD8 CTL and suggests that it may contribute to lysis of HIV-infected cells in vitro and in vivo.