Earlier presentation of age-related complications in people with HIV (on ART), is in part attributed to HIV accelerating the loss of immune function in older people. T cells are immune cells that are critical for the control of both cancers and infections. This project focuses on whether i) the protein Foxo1, a master regulator of multiple functions in T cells, is dysregulated by both age and HIV infection and ii) increased Foxo1 expression can improve T cell function in older people with HIV. In this application, we will perfomed detailed immune analysis of ~ 50 people with HIV on antiretroviral therapy. Methods used in the application include flow and mass cytometry and multiplex ELISA. Analyses will integrate demographic and clinical data to devise biostatistical models to examine the impact of age and HIV immune dysregulation on FoxO1 expression and activity in T cells.