Contributions of CD4(+), CD8(+), and CD4(+)CD8(+) T cells to skewing within the peripheral T cell receptor beta chain repertoire of healthy macaques

Diversity in the peripheral T cell receptor repertoire of rhesus (Macaca mu latta) and pig-tailed macaques (Macaca nemestrina) has been studied by exam ining the profile of CDR3 lengths in TCR beta chains. Expressed CDR3 length distribution profiles for individual TCRBV families were obtained from tot al peripheral blood mononuclear cells (PBMC) and T cell subsets isolated fr om PBMC. These studies reveal that the T cell receptor repertoire of PBMC f rom healthy macaques often exhibits skewing in TCRBV family CDR3 profiles. The skewing of TCRBV family CDR3 profiles was evident as discrete expanded length(s) and was detected in up to 50% of the PBMC profiles. Analyses of s eparated T cell populations demonstrated that the CD8(+) T cell subset was responsible for the majority of observed skewing in CDR3 length profiles. H owever, CD4(+) T cells were also shown to contribute to the skewed peripher al PBMC repertoire in these animals. While certain TCRBV families frequentl y displayed skewed profiles, there was no concordance in the particular CDR 3 lengths expanded among the different animals. Furthermore, an additional feature of the peripheral blood of the animals studied was the presence of an unusual population of extrathymic CD4(+) and CD8(+) (double-positive)T c ells (up to 9.6% in the PBMC of rhesus macaques). The double-positive T cel ls could be differentiated from CD4 single-positive and CD8 single-positive T cells by their increased surface expression of LFA-1 and decreased CD62L expression. The percentage of the double-positive T cells was higher in rh esus than pig-tailed macaques and contributed substantially to the peripher al T cell repertoire. Human Immunology 60, 209-222 (1999). (C) American Soc iety for Histocompatibility and Immunogenetics, 1999 Published by Elsevier Science Inc.