The selection of the α,β heterodimeric T-cell receptor for antigen

T cells express α,β heterodimeric receptor proteins which are involved in the MHC-restricted binding of antigen (1,2). The nucleotide sequences of T-cell receptor genes(3-6) have not provided an obvious explanation for the 'MHC-ness' of T-cell specificity or the different specificity of T-cell subsets. The binding of α,β heterodimeric T-cell receptors has not yet been studied in solution so it is possible that T cells express additional molecules that are involved in antigen binding. Recent experimental data(7), reviewed in our last issue (Immunol. Today 1986, 7, 308-311) indicate that the α,β heterodimer alone is responsible for the MHC-restricted specificity of T cells. Here, Harald von Boehmer discusses the implications of these data and presents a model for the selection of α,β heterodimeric T-cell receptors during T-cell differentiation in the thymus.