J Infect Dis. 2009 Jul 15; 200(2):236-43.

PubMed ID: 19505257

Differential HIV epitope processing in monocytes and CD4 T cells affects cytotoxic T lymphocyte recognition

Lazaro E, Godfrey SB, Stamegna P, Ogbechie T, Kerrigan C, Zhang M, Walker BD, Le Gall S

The ability of cytotoxic T lymphocytes (CTLs) to clear virus-infected cells is dependent on the presentation of viral peptides processed intracellularly and displayed by major histocompatibility complex class I. Most CTL functional assays use exogenously added peptides, a practice that does not account for the kinetics and quantity of antigenic peptides produced by infectable cells. Here, we examined the relative ability of 2 major human immunodeficiency virus-infectable cell subsets-CD4 T lymphocytes and monocytes-to produce antigenic peptides, using cytosol as a source of peptidases and mass spectrometry to define the degradation products. We show clear subset-specific differences in the kinetics of peptide production and the ability of the peptides produced to sensitize cells for lysis by CTLs, with primary CD4 T lymphocytes having significantly lower proteolytic activity than monocytes. These differences in epitope processing by cell subsets may affect the efficiency of CTL-mediated clearance of infected subsets and contribute to the establishment of chronic infection.