The molecular basis of MHC-restricted antigen recognition by T cells

In order to determine the contribution of the clonotypic T cell receptor (Ti) alpha beta heterodimer to the antigen/MHC specificity of mature T cells, we have transfected cloned Ti alpha and/or beta genes into either human or mouse T cells, and analyzed the transfectants for Ti-T3 expression and responses to antigen and Ia molecules. Our analysis establishes that a single receptor structure (the Ti alpha beta heterodimer) is necessary and sufficient to define the dual specificity of T cell antigen recognition and suggests that in at least certain instances Ti beta chains play a predominant role in MHC restriction specificity, raising the possibility of a "one receptor, two sites" model of T cell recognition.