HIV-1-Infected CD4 T Cells Present MHC Class II-Restricted Epitope via Endogenous Processing.

HIV-1-specific CD4 T cells (Ts) play a critical role in controlling HIV-1 infection. Canonically, Ts are activated by peptides derived from extracellular ("exogenous") Ags displayed in complex with MHC class II (MHC II) molecules on the surfaces of "professional" APCs such as dendritic cells (DCs). In contrast, activated human Ts, which express MHC II, are not typically considered for their APC potential because of their low endocytic capacity and the exogenous Ag systems historically used for assessment.