Chicken γδ T Cells

Abstract

Functional and genetic studies of the γδ T cell receptor (TCR) have progressed in reverse order compared to the study of αβ T cells (reviewed by Raulet 1989). A wealth of information about the αβ T cell population and its function was available before the genes for the αβ TCR were cloned. Studies of the αβ TCR repertoire and gene expression then helped elucidate molecular mechanisms for generating diversity of the αβ T cell repertoire and the nature of antigen recognition by αβ T cells. However, the identification of a third TCR locus (γ), and the subsequent discovery that a fourth TCR chain (δ) was encoded by genes embedded within the TCR-α locus, led to the description of the γδ TCR expressed by a T cell subpopulation with no known function. Over the last 10 years, laboratories around the world have been trying to assign functional roles for T cells expressing the γδ TCR. Studies of mouse and human γδ T cells have revealed many interesting differences in the biology of γδ vs. αβ T cells, such as tissue distribution, repertoire restrictions, requirement for a thymus for their development, and lack of classical MHC restriction (for reviews see Allison 1993; Haas et al. 1993; Kronenberg 1994; Lefrancois and Puddington 1995).