Detection of simian immunodeficiency virus Gag-specific CD8(+) T lymphocytes in semen of chronically infected rhesus monkeys by cell staining with a tetrameric major histocompatibility complex class I-peptide complex

Evaluation of human immunodeficiency virus type I-specific mucosal cytotoxi c T lymphocytes can he hampered bg limited cell yields from mucosal sites. We sought to characterize virus-specific CD8(+) T lymphocytes with cytotoxi c activity in the male genital tracts of SIVmac-infected rhesus monkeys by using a peptide epitope-specific functional T-cell assay and a tetrameric m ajor histocompatibility complex class I-peptide complex, This tetrameric co mplex was constructed with the rhesus monkey HLA-A homolog molecule Mamu-A* 01 and a dominant-epitope 9-amino-acid fragment of SIVmac Gag (p11C, C-M). The proportion of tetramer-positive CD8(+) T cells in semen of SIVmac infec ted monkeys ranged from 5.9 to 22.0%. By the use of a standard Cr-51 releas e assay, these cells were found to have peptide epitope-specific cytolytic activity after in vitro expansion. Four-color flow-cytometric analysis of t hese seminal tetramer-positive CD8(+) T cells demonstrated that they expres s memory-associated (CD62L(-) CD45RA(-)) and activation-associated (CD11a() Fas(+) HLA-DR+) molecules. The present experiments illustrate the power o f tetramer technology for evaluating antigen-specific CD8(+) T lymphocytes in a mucosal tissue compartment.