Biology of murine γδ T cells

Murine lymphocytes express either a T-cell receptor αβ or a γδ heterodimer. The function of αβ cells are well characterized, while γδ cells remain an enigmatic population. In the mouse, γδ cells appear in significant proportions in the epithelia of various nonlymphoid tissues such as the skin, intestine, tongue, lung, and reproductive organs. While γδ T-cell subsets with distinct antigen receptor repertoires are associated with certain organs, diversified populations of γδ cells showing heterogeneous TCR phenotypes, as a result of junctional region diversification and usage of different V chains, can be found in the lymphoid organs and in the intestinal epithelia. Recent evidence has shown that γδ cells might recognize heat shock proteins, possibly in association with classical and nonpolymorphic MHC molecules. Together with their tissue distribution, γδ cells may represent the first line of defense of the immune system. γδ Cells are the first T cells to colonize the thymus. Intriguingly, there is more evidence to support the hypothesis that they might also affect the development of αβ cells and other hematopoietic stem cells.