Inhibition of T Cells by Hiv - 1 Gp 120 1 ” 2 0 0 K 4 ’ 116 K - 9 3 K 4 68 K - 43 K -

We investigated mechanisms by which the soluble native envelope glycoprotein gpl20 of the human immunodeficiency virus (HIV-1) suppresses antigen-driven T cell responses. For this study, exogenous interleukin-2 (IL-2)independent, antigen-specific, CD4 positive, human T-cell clones were developed by cyclic restimulation with soluble tetanus toxoid antigen. In the presence of soluble antigen and antigen-presenting cells (APC), T-cell clones proliferated and secreted IL-2. Purified gp120 suppressed the proliferative responses of the T-cell clones with concomitant suppression of IL-2 secretion; proliferative responses of CD8+ T cells preincubated with gp120 were not inhibited. A short pulse of 20 minutes with gp120 was sufficient to inhibit the proliferative response of the T-cell clones. Anti-CD3 monoclonal antibody (MoAbI-driven pro-