HIV-induced deletion of antigen-specific T cell function is MHC restricted.

When antigen-specific T cells are pulsed by antigen-presenting cells (APC) in the presence of HIV they are functionally deleted following subsequent exposure to syngeneic APC in the absence of HIV. Recombinant soluble HIV envelope (gp120) is able to induce a similar effect which, unlike that induced by HIV, is reversible. Neither HIV nor gp120 affect the ability to respond to IL-2. Thus it is only antigen-specific responses involving the T cell receptor pathways and CD4/MHC class II interaction that appear to be inhibited by HIV-1 and gp120. Furthermore, the functional impairment caused by HIV-1 is specific to the T cells that respond to the antigen in co-culture with HIV, as there is no apparent effect on 'bystander'-activated T cells specific for another antigen. Antigen-specific T cell lines may be deleted by a signalling mechanism which involves molecules other than gp120/CD4 but still requires MHC class II restriction.