RESTRICTED USAGE OF T-CELL RECEPTOR V-ALPHA SEQUENCE AND VARIABLE-JOINING PAIRS AFTER NORMAL T-CELL DEVELOPMENT AND BONE-MARROW TRANSPLANTATION

TCR Valpha3 and Valpha5 transcripts in PBLs from healthy individuals o f multiple age groups and from BMT recipients were analyzed. PCR, clon ing, and sequencing studies revealed significant V-J junctional divers ity among TCR transcripts from all tested blood samples, as provided b oth by N/P-region addition and exonuclease activity. However, results illustrated restrictions in TCRalpha diversity at several additional l evels. First, Valpha5 and Valpha3 gene families, which were expected t o be composed of multiple members, were dominated in each case by a si ngle sequence at the transcript level. Second, restrictions existed in V-J pairing in that Jalpha genes, which were encoded toward the 5' re gion of the locus, were rearranged frequently with Valpha3 and rarely with Valpha5. Conversely, Jalpha genes encoded toward the 3' region of the locus preferentially rearranged with Valpha5. Healthy individuals showed few differences with regard to V-J pairing patterns, while one of three BMT recipients demonstrated a skewed usage of 3' Jalpha gene s. In total, results demonstrated qualitative restrictions that may li mit the working TCR repertoire in human peripheral tissues, both among BMT recipients and their healthy donors.