Predominant use of a particular α-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 α-chain gene from two independent keyhole limpet hemocyanin (KLH)-specific suppressor T cell (T_s) hybridomas (BW5147 x C57BL/6 KLH-T_s. These nucieotide sequences were compared with those of germline DNA from kidney and also with cDNA of α-chain (VJ_α28l) previously isolated from T_s hybridoma (348-281) with KLH/H-2^b T_s activity. The entire V_α, and J_α sequences of all three T_s hybridomas were exactly identical and were encoded by the germline V_α, and J_α gene segments without any mutations, except for 2-nucieotide deletions from both the 3' end of V_α and the 5' end of J_α 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-T_s hybridomas, further analyzed, also possessed the same α-chain, indicating the preferential usage of the particular α-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 α-chain mRNA in the thymus and spleen of unprimed C57BL/6 mice was found to be of this particular α-chain. These results suggest that the repertoire of KLH-T_s is strictly limited.