Expression of the human T cell receptor Vβ repertoire

We have used a sensitive assay, based on amplification of cDNA by the polymerase chain reaction, to determine in a variety of human tissues the relative levels of expression of the genes coding for each of the twenty families of human TcR Vβ. We have determined the diversity of the expressed TcR Vβ repertoire early in the development of the immune system. We have shown that the full TcR Vβ repertoire is expressed early into the second trimester; the expressed repertoire is as diverse at this point, in both fetal thymus and spleen, as it is in mature thymus and peripheral blood lymphocytes. In addition the relative expression in the fetal thymus of each Vβ gene is conserved to a large extent in the fetal spleen.