Distinct pattern of human Vdelta1 gammadelta T cells recognizing MICA.

Gammadelta T cells represent one unique recognition pattern, the limited recognition, which distinguishes from the specific recognition for alphabeta T cells and pattern recognition for macrophages. Vdelta1 gammadelta T cell is the major subset of human gammadelta T cells, which predominates in mucosal tissue including the intestinal epithelia. Presently, a few antigens that human Vdelta1TCR can recognize have been identified. Among them, MHC class I chain-related molecules A (MICA) have been studied most intensively. Besides Vdelta1TCR, MICA is also the ligand of NKG2D, a C-type lectin-like activating immunoreceptor. In human, only Vdelta1 cells can simultaneously express both types of receptors of MICA while NK cells, alphabetaT cells and other subsets of gammadelta T cells likewise express NKG2D. Although the precise mechanisms are still enigmatic, this distinct pattern of Vdelta1 cells recognizing MICA predicts unique biological significance of Vdelta1 cells in immune defense. Recent years, some progresses have been made in this issue. In this review we summarize the related reports and put forward some novel views based on our group's studies.