TBDs are associated with a higher prevalence of activated and exhausted cells. Several activation and exhaustion markers were identified in a T-cell subpopulation enriched in patients with TBD; additionally, Fas receptor (CD95) and PD-1 overexpression could explain the decline of CD4+ T and B cells in that group. (A) viSNE map showing a population of CD4+ effector cells being enriched in patients. (B) Percentages of the subset defined in panel A. (C-D) Expression of CD95 and PD-1 in CD4+ and CD8+ cells, respectively. (E) Expression of CD95 in B cells. (F) Percentage of infiltrating monocytes expressing CXCR3 identified in CD3– cells. (G) Infiltrating CXCR3+ monocytes highlighted on viSNE maps, with expansion in patients with TBD. ∗P ≤ .05; ∗∗∗∗P ≤ .0001.TBD, telomere biology disorder; TEM, T effector memory; t-SNE, t-distributed stochastic neighbor embedding.