Telomere length was measured in PBMC DNA using quantitative PCR and shown for IPF, non-IPF, and non-transplant referents (healthy) both pre-transplant and at 2 years post-transplant (A). Telomere length was shorter in IPF subjects compared with non-IPF and non-transplant referents as assessed by unadjusted GEE models (P < 0.001). For Non-IPF versus healthy, we observed P = 0.09. (B) Telomere length measurements are shown stratified by cytokine profile cluster, as identified in Figure 4. After multiple comparison adjustments clusters 3 and 4, with impaired cytokine production, were found to have shorter telomere lengths than the clusters 1 and 2. Percent proliferation to matched or single donor alloantigens is shown versus telomere length for CD8+ T cells (C) and CD4+ Tconv (D). P-values represent statistical significance for the association of proliferation with telomere length as assessed by unadjusted GEE models.