In the course of a mixed lymphocyte culture, memory cells are produced which can give rise to a large secondary cytotoxic lymphocyte response on reexposure to the sensitizing alloantigen. We have studied the lineage of these memory cells using a clonal assay for precursors of cytotoxic T lymphocytes (CLP). Our data provide conclusive evidence that individual CLP, upon stimulation with alloantig...

During the first weeks of human immunodeficiency virus-1 (HIV-1) infection, cytotoxic T-lymphocytes (CTLs) select for multiple escape mutations in the infecting HIV population. In recent years, methods that use escape mutation data to estimate rates of HIV escape have been developed, thereby providing a quantitative framework for exploring HIV escape from CTL response. Current methods for escap...

The progress of HIV is accompanied by the infection and decline of the population of CD4+ cells. This reduction in cells results from both cytolytic influences of the virus and virus-specific cytotoxic T-cell (CTL) responses. We seek to characterize the extent of CD4+ reduction caused by HIV-specific CTLs at equilibrium. Here we show that intermediate levels of cytotoxic killing of infected cel...

CTLA-4 was first identified in 1991 as a second receptor for the T cell costimulation ligand B7. Uncertainties about its biological function plagued the early years after its discovery until 1995, when it was confirmed to be an inhibitor of T cell responses. CTLA-4 has since scored in the clinic as a target for antitumor therapy and as a soluble inhibitor of autoimmunity.