CD4(-)CD8(-) T cells bearing invariant V alpha 24J alpha Q TCR alpha-chain are decreased in patients with atopic diseases

Atopic disorders are caused by disregulated activation of T helper 2 (Th2) cells that produce IL-4 and IL-5. Because the presence of IL-4 potently augments the differentiation of naive T cells into Th2 cells, it is important to seek the cell population which provides IL-4 for naive T cells. Recently, a unique subpopulation of T cells, natural killer (NK) T cells, has been shown to produce a large amount of IL-4 upon activation, suggesting their regulatory role in initiation of Th2 cell differentiation. To determine whether NK T cells play a regulatory role in human Th2 cell-mediated atopic diseases, we analysed the frequency of invariant V alpha 24J alpha Q CD4(-)CD8(-) double-negative (DN) T cells, human NK T cells, in patients with atopic asthma and atopic dermatitis. We also studied cytokine production from V alpha 24(+) V beta 11(+) DN T cells, which comprise most of V alpha 24J alpha Q DN T cells. We found that the invariant V alpha 24J alpha Q DN T cells were greatly diminished in patients with asthma and atopic dermatitis. On the other hand, there was no significant difference in V alpha 24(+) CD4(+) T cells possessing invariant V alpha 24J alpha Q TCR between healthy subjects and atopic patients. We also found that V alpha 24(+) V beta 11(+) DN T cells from healthy subjects predominantly produced interferon-gamma (IFN-gamma) but not IL-4 upon activation. These results suggest that NK T cells may not be essential for human atopic disease and that the disappearance of NK T cells, most of which produce IFN-gamma, may be involved in the pathogenesis of atopic diseases.