Figure 1.

Replicative stress and contraction of TCR diversity. (a) With normal aging, peripheral T cells develop progressive telomeric erosion as evidence of replicative stress. (b) Frequencies of TCR excision circle (TREC)-positive T cells decline as a consequence of thymic dysfunction and cumulative peripheral turnover. Both processes are accelerated in patients with rheumatoid arthritis (RA). (c) The TCR repertoire of naive T cells in RA (light-shaded area) is markedly contracted compared with age-matched controls (dark-shaded area). Individual naive T cells in RA are present at higher frequencies and are of larger clonal sizes, resulting in a lower number of different TCRs. bp, base pairs.