Frequency and phenotyping of human immunodeficiency virus (HIV)-specific CD8(+) T cells in HIV-infected children, using major histocompatibility complex class I peptide tetramers

HLA-A*02 tetramers complexed to human immunodeficiency virus (HIV) Gag SLYN TVATL and HIV Pol ILKEPVHGV peptides were used to characterize HLA class I- restricted CD8(+) T cells in 41 HIV-infected children. The frequencies and the phenotype of specific circulating CD8(+) T cells were determined in who le-blood samples by means of cytometric analysis. Background staining of 13 HLA-A*02-negative patients showed that the frequency of CD8(+) T cells was <0.01%. Of the 28 HLA-A*02-positive patients, blood samples from 26 staine d positive at least once the Gag tetramer (mean CD8(+) T cells, 0.87%; rang e, 0.1%- 3.9%), and blood samples from 21 stained positive for the Pol tetr amer (mean CD8(+) T cells, 0.59%; range, 0.1%-5.5%). The tetramer-binding c ells were CD28(-), CD45RA(-), CD45RO(+), HLA-DR+, and CD69(-) T lymphocytes . HIV-specific CD8(+) T cells can be detected easily in peripheral blood of HIV-infected children, using HLA tetramers combined with HIV peptides. The se cells are memory activated CD28(-)CD8(+) T lymphocytes.