Predominant use of a particular alpha-chain in suppressor T cell hybridomas specific for keyhole limpet hemocyanin

Abstract

We isolated and sequenced the rearranged genomic variable (V) and joining (J) gene segments of T cell receptor alpha-chain gene from two independent keyhole limpet hemocyanin (KLH)-specific suppressor T cell (Ts) hybridomas (BW5147 x C57BL/6 KLH-Ts). These nucleotide sequences were compared with those of germline DNA from kidney and also with cDNA of alpha-chain (VJ alpha 281) previously isolated from Ts hybridoma (34S-281) with KLH/H-2b Ts activity. The entire V alpha and J alpha sequences of all three Ts hybridomas were exactly identical and were encoded by the germline V alpha and J alpha gene segments without any mutations, except for 2-nucleotide deletions from both the 3' end of V alpha and 5' end of J alpha gene segments, respectively, and a 1-nucleotide (guanine) insertion in the junctional (N) region which was not encoded by the germline gene. Six additional KLH-Ts hybridomas, further analyzed, also possessed the same alpha-chain, indicating the preferential usage of the particular alpha-chain in these hybridomas. As chromosome analysis demonstrated a different pattern in each clone, these hybridomas appear to be independent. More surprisingly, 0.5-1.5% of the total functional T cell alpha-chain mRNA in the thymus and spleen of unprimed C57BL/6 mice was found to be of this particular alpha-chain. These results suggest that the repertoire of KLH-Ts is strictly limited.