T cell receptor repertoire differences between African Americans and Caucasians associated with polymorphism of the TCRBV3S1 (V beta 3.1) gene.

The generation of TCR diversity occurs primarily through rearrangement of germline DNA. Genetic polymorphism of the TCR chains appears to be a rarer mechanism for generating repertoire differences between races. Flow cytometric analysis of the TCR V beta repertoire in a population of healthy African Americans (n = 30) and Caucasians (n = 30) revealed a significant difference in the frequency of cells bearing V beta 3.1, but not V beta 2, V beta 5.1, V beta 5.2-5.3, V beta 6.7, V beta 8.1-8.2, V beta 12.1, V beta 13.3, or V beta 19. African Americans had a significantly lower frequency of V beta 3.1+ cells, in both the CD4+ (2.55 +/- 0.36% vs 4.85 +/- 0.43%, p = 0.0001) and the CD8+ (3.03 +/- 0.54% vs 5.32 +/- 0.57%, p = 0.004) population than did Caucasians, and this difference was independent of the age of the individuals. Analysis of genomic DNA revealed that the observed difference in frequency of V beta 3.1+ cells correlated with a recently described polymorphism of the recombination signal sequence of the TCRBV3S1 gene. Allele 1, associated with a lower frequency of V beta 3.1+ cells, was more commonly present in African Americans (0.68 vs 0.43), whereas allele 2, associated with a higher frequency of V beta 3.1+ cells, was more commonly present in Caucasians (0.31 vs 0.56). This study demonstrates the potential for TCR repertoire differences, based on genetic polymorphism, between African Americans and Caucasians.