Fig. 1.

Age is associated with a modest decrease in diversity of the TCRB repertoire. TCRB sequences were obtained from replicate samples of naïve (A and B) and memory (C and D) CD4 and CD8 T cells. A lower bound of TCRB richness was estimated by applying nonparametric statistics using the Chao2 estimator. Results are shown for nucleotide (A and C) and derived amino acid sequences (B and D). Estimates were compared by Wilcoxon–Mann–Whitney test. Increase in age is associated with a decline in richness of naïve CD4 and CD8 T cells; however, the repertoire in the elderly remains highly diverse. Richness in CD4 and CD8 memory T cells markedly differed, whereas the impact of age was negligibly small.