Characteristics of T-cell receptor Valpha24JalphaQ T cells, a human counterpart of murine NK1 T cells, from normal subjects.
BACKGROUND
In mice, natural killer (NK) T cells are specialized subsets of T cells that express an invariate T cell receptor (TCR) alpha chain and NK markers. In particular, murine NK1(+/-) T cells rapidly produce IL-4 and function as regulatory T cells.


OBJECTIVE
We investigated the distribution of invariate TCR Valpha24JalphaQ T cells in CD4(-)CD8(-) double-negative (DN) and CD4(+) T cell populations of healthy individuals. We also studied the NK phenotypes and IL-4 production of Valpha24JalphaQ T cells.


METHODS
The frequency of Valpha24(+/-) DN or CD4(+/-) T cells was determined by three-color FACS analysis, and subsequently the frequency of Valpha24JalphaQ rearrangement among Valpha24(+/-) DN or CD4(+/-) T cells was determined by sequencing.


RESULTS
While the majority of DN Valpha24(+) T cells (68% to 88%) possessed TCR Valpha24JalphaQ, few of CD4(+) Valpha24(+) T cells (0.4% to 4%) did, indicating that Valpha24JalphaQ T cells are a major population of DN T cells, but not of CD4(+) T cells, in healthy subjects. The DN Valpha24JalphaQ T cells expressed a natural killer surface receptor NKR-P1A and CD56, but not CD16, on the cell surface. Moreover, DN Valpha24JalphaQ T cells promptly expressed IL-4 mRNA by stimulation with anti-Valpha24 monoclonal antibody in vitro.


CONCLUSIONS
From these phenotypic and functional similarities of human DN Valpha24JalphaQ T cells with murine NK1(+) Valpha14Jalpha281 T cells, we conclude that DN Valpha24JalphaQ T cells are a counterpart of murine NK1(+) T cells, suggesting that they may play a regulatory role in autoimmune responses in vivo.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000954:Antigens, Surface / Q000032:analysis; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry; D006801:Humans; D015847:Interleukin-4 / Q000235:genetics; D007694:Killer Cells, Natural; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis* / Q000097:blood; D013601:T-Lymphocytes / Q000737:chemistry* / Q000166:cytology