Changes in mean TRF length in neutrophils of fully engrafted HSCT recipients.

Telomere length in donors is indicated at time zero. (A) R1 to R4. (B) R5 to R7 and R10. (C) R8, R9, R14, R15, and R18. (D) R11 to R13, R16, and R17. (E) R19 to R22. (F) R23 to R25. To facilitate comparison, (A,C) recipients sampled 2 months after HSCT (in addition to other times) are presented together; (F) those sampled on 4 occasions in the first 60 days are shown together. On the basis of analysis of paired control samples, changes in mean TRF length exceeding 270 bp may be regarded as significant. Note that, although telomeres in recipients tended to be shorter than in their respective donors, they were not always so. Many recipients showed marked fluctuations in telomere length over the 12-month period of observation. The timing and extent of these fluctuations appear highly variable and random.