Restricted usage of T-cell receptor Vα sequence and variable-joining pairs after normal T-cell development and bone marrow transplantation

Abstract

TCR Vα3 and Vα5 transcripts in PBLs from healthy individuals of multiple age groups and from BMT recipients were analyzed. PCR, cloning, and sequencing studies revealed significant V-J junctional diversity among TCR transcripts from all tested blood samples, as provided both by N/P-region addition and exonuclease activity. However, results illustrated restrictions in TCRα diversity at several additional levels. First, Vα5 and Vα3 gene families, which were expected to be composed of multiple members, were dominated in each case by a single sequence at the transcript level. Second, restrictions existed in V-J pairing in that Jα genes, which were encoded toward the 5′ region of the locus, were rearranged frequently with Vα3 and rarely with Vα5. Conversely, Jα genes encoded toward the 3′ region of the locus preferentially rearranged with Vα5. Healthy individuals showed few differences with regard to V-J pairing patterns, while one of three BMT recipients demonstrated a skewed usage of 3′ Jα genes. In total, results demonstrated qualitative restrictions that may limit the working TCR repertoire in human peripheral tissues, both among BMT recipients and their healthy donors.