A population of murine γδ T cells that recognize an inducible MHC class lb molecule

Although gamma delta T cells are implicated in regulating immune responses, gamma delta T cell-ligand pairs that could mediate such regulatory functions have not been identified. Here, the expression of the major histocompatibility complex (MHC) class Ib T22 and the closely related T10 molecules is shown to be activation-induced, and they confer specificity to about 0.4% of the gamma delta T cells in normal mice. Thus, the increased expression of T22 and/or T'10 might trigger immunoregulatory gamma delta T cells during immune responses. Furthermore, the fast on-rates and slow off-rates that characterize this receptor/ligand interaction would compensate for the low ligand stability and suggest a high threshold for gamma delta T cell activation.