Role of the T cell receptor alpha chain in the development and phenotype of naturally arising CD4+CD25+ T cells

The T cell receptor alpha chain repertoire and the possible influence of the alpha chain on the development and phenotype of naturally arising mouse CD4+CD25+ T cells have not been extensively analysed. We used all available Vα-specific monoclonal antibodies and a sensitive multiplex genomic DNA PCR assay to study the Vα repertoire of CD4+CD25+ T cells in normal mice. To address whether CD4+CD25+ T cells express two TCR alpha chains, we have carried out four-colour flow cytometry using combinations of the available anti-Vα reagents in mice where one allele of the TCRA locus had been inactivated. Results indicate that the Vα repertoire of CD4+CD25+ T cells is as diverse as their CD25− partners. In addition, CD4+CD25+ T cells develop normally in Tcrα+/− mice and we show for the first time that despite expressing only one TCRα chain, they retain their characteristic CD4low, CD3low, TCRβlow, CD5high, CD45RBlow and cytoplasmic CD152high phenotype.