T cell receptor alpha and beta gene expression in a murine antigen-specific T suppressor lymphocyte clone with...

The composition of alpha and beta TCR genes was analyzed in a murine BSA-specific Ts cell clone with cytolytic potential. The isolated poly(A)+ mRNA from Ts cell clone BVI/5 was used to construct a cDNA library in the bacteriophage lambda gt11. Full-length cDNA clones specific for TCR alpha and TCR beta genes have been detected and isolated by hybridization with specific oligonucleotide probes. The functional rearranged TCR alpha gene is composed of a member of the V alpha 1 family, the junctional gene J alpha TT11 and C alpha. The gene segments V beta 13, D beta 2.1, J beta 2.4, and C beta 2 form the functional rearranged TCR beta gene. Furthermore, a nonfunctional TCR alpha gene transcript has been detected, where a V alpha 8 gene is rearranged to a so far not described J alpha gene segment (J alpha BVI). A stop codon in its junctional region is responsible for this non-functional transcript. By using Southern blot analysis, the described rearranged TCR genes can be detected in the J alpha junctional region and in the J beta 2 cluster on the genomic DNA level. Immunoprecipitation studies with the KT3 anti-CD3 mAb and flow microfluorimetry analysis with the H57-597 anti-TCR-alpha/beta mAb show that TCR/CD3 complexes are synthesized and expressed on BVI/5 Ts cells. Taken together, the cDNA sequencing data, the protein studies, and the specificity of Ag recognition demonstrate that the BVI/5 Ts cell clone not only transcribes the TCR alpha and beta genes but also expresses a functional BSA-specific receptor.