γδ T cell development — having the strength to get there

γδ T cells play critical roles in immune regulation, tumour surveillance and specific primary immune responses. Mature γδ cells derive from thymic precursors that also generate αβ T cells. Recent reports have highlighted the impact of the strength of signal received via the T cell receptor on T cell lineage commitment, and the importance of cross-talk between committed αβ thymocytes and bipotential progenitors for normal γδ T cell differentiation. Studies on T cell receptor-mediated selection of γδ cells have supported the view that these unconventional T cells are positively rather than negatively selected on cognate self antigen.