Characteristics of T-cell receptor Vα24JαQ T cells, a human counterpart of murine NK1 + T cells, from normal subjects

Abstract

Background: In mice, natural killer (NK) T cells are specialized subsets of T cells that express an invariate T cell receptor (TCR) α 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 Vα24JαQ 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 Vα24JαQ T cells. Methods: The frequency of Vα24 ± DN or CD4 ± T cells was determined by three-color FACS analysis, and subsequently the frequency of Vα24JαQ rearrangement among Vα24 ± DN or CD4 ± T cells was determined by sequencing. Results: While the majority of DN Vα24 + T cells (68% to 88%) possessed TCR Vα24JαQ, few of CD4 + Vα24 + T cells (0.4% to 4%) did, indicating that Vα24JαQ T cells are a major population of DN T cells, but not of CD4 + T cells, in healthy subjects. The DN Vα24JαQ T cells expressed a natural killer surface receptor NKR-P1A and CD56, but not CD16, on the cell surface. Moreover, DN Vα24JαQ T cells promptly expressed IL-4 mRNA by stimulation with anti-Vα24 monoclonal antibody in vitro. Conclusion: From these phenotypic and functional similarities of human DN Vα24JαQ T cells with murine NK1 + Vα14Jα281 T cells, we conclude that DN Vα24JαQ T cells are a counterpart of murine NK1 + T cells, suggesting that they may play a regulatory role in autoimmune responses in vivo. (J Allergy Clin Immunol 1999;103:S445-51.)