γδ T Lymphocytes in Mice and Man: A Review

With the discovery of a second type of T cells, those expressing T cell receptor (TCR) γδ, the question has arisen: “What contribution do these cells make to the immune system?” We review here how TCR diversity is generated at the molecular level and what this means for the capability of TCR αβ and TCR γδ to recognize a variety of antigenic peptides in the context of conventional and alternative presenting molecules. We will discuss how tissue distribution and repertoire selection of γδ T cells are in part developmentally regulated and how the repertoire may be further shaped by antigenic stimulation. Critical investigation of the causes and consequences of γδ T cell proliferation in human disease situations will hopefully provide insight into the normal functions of this elusive T cell population.