Clonal CD8+ T cell expansions in peripheral blood from human immunodeficiency virus type 1-infected children.

The T cell receptor (TCR) repertoires of 24 human immunodeficiency virus (HIV) type 1-infected children were determined by flow cytometry in combination with sequencing of the highly variable TCR complementarity-determining region 3, permitting a quantitative and qualitative assessment of TCR repertoire. Expanded subsets of CD8(+) cells expressing a particular TCR beta-chain variable region were more commonly identified in HIV-1-infected children than in healthy control subjects (75% vs. 13.5%; P<.0001). Older age and lower percentage of CD4(+) cells were correlated with expansions. Oligoclonal populations occupied 71%-95% of each expanded subset, and predominant clones had high absolute counts. There was evidence of functional differentiation to CD28(-) effector cytotoxic T lymphocytes, and cells bearing identical TCRs were identified in both CD28(+) and CD28(-) cell populations. HIV-1 specificity was observed for expanded clones. Children with expansions were not more likely to have increased numbers of CD8(+) T cells, a finding consistent with the possibility that the CD8(+) TCR repertoire has limited diversity.