Surface expression of only γδ and/or αβ T cell receptor heterodimers by cells with four (α, β, γ, δ) functional receptor chains

Surface expression of TCR dimers by cells synthetizing three or four distinct types of receptor chains was analyzed. Cells containing intact γ, α, and β chains had only γδ dimers on the cell surface. In human PEER cells, addition of a functional α chain led to the loss of γδ dimer expression and expression of only αβ dimers. This result was not due to transcriptional down-regulation of the γ or δ loci. In murine cells expressing all four chains, both γδ and αβ dimers could be demonstrated on a single cell. No other chain combinations (αγ, αδ, βγ, βδ) were detected. Thus, there is stringent control of assembly and/or transport of TCR heterodimers, such that functional receptors consist only of αβ and γδ pairs, and no additional repertoire diversity is generated by cross pairing.