Comparative analysis of cytotoxic T lymphocytes in lymph nodes and peripheral blood of simian immunodeficiency virus-infected rhesus monkeys

Most studies of human immunodeficiency virus type 1 (HIV-1)-specific cytoto xic T lymphocytes (CTL) have been confined to the evaluation of these effec tor cells in the peripheral blood. What has not been clear is the extent to which CTL activity in the blood actually reflects this effector cell funct ion in the lymph nodes, the major sites of HIV-1 replication. To determine the concordance between CTL activity in lymph nodes and peripheral blood ly mphocytes (PBL), CTL specific for simian immunodeficiency virus of macaques (SIVmac) have been, characterized in lymph nodes of infected, genetically selected rhesus monkeys by using both Gag peptide-specific functional CTL a ssays and tetrameric peptide-major histocompatibility complex (MHC) class I molecule complex staining techniques. In studies of six chronically SIVmac -infected rhesus monkeys, Gag epitope-specific functional lytic activity an d specific tetrameric peptide-MHC class I staining were readily demonstrate d in lymph node T lymphocytes. Although the numbers of tetramer-binding cel ls in some animals differed from those documented in their PBL, the numbers of tetramer-binding cells from these two different compartments were not s tatistically different. Phenotypic characterization of the tetramer-binding CD8(+) lymph node T lymphocytes of the infected monkeys demonstrated a hig h level of expression of the activation-associated adhesion molecules CD11a and CD49d, the Fas molecule CD95, and MHC class II-DR. These studies docum ented a low expression of the naive T-cell marker CD45RA and the adhesion m olecule CD62L, This phenotypic profile of the tetramer-binding lymph node C D8(+) T cells was similar to that of tetramer-binding CD8(+) T cells from P BL. These observations suggest that characterization of AIDS virus-specific CTL activity by sampling of cells in the peripheral blood should provide a reasonable estimation of CTL in an individual's secondary lymphoid tissue.