Skip to main content
. 2012 Jan 18;7(1):e30264. doi: 10.1371/journal.pone.0030264

Figure 6. Change in relative telomere length of purified NK cells after expansion on aAPCs with or without membrane-bound cytokines.

Figure 6

NK cells were purified from normal donor buffy coats. An aliquot was viably frozen for later comparison, and the remaining cells were stimulated with IL-2 and irradiated aAPCs bearing no cytokine (Clone 9), mbIL15 (Clone 4), mbIL21 (Clone 9.mbIL21), or IL-15 fused with a linker to IL15Rα (Clone 27). (A) Telomere length of the NK cells was determined after 7 days by flow cytometry after hybridization with FITC-labeled PNA probe for the TTAGGG telomeric repeat sequence. Mean fluorescence of the NK cells was normalized to the reference cell line CEM-1301, and the telomere length of expanded NK cells was normalized to that of fresh NK cells for each individual donor. A 1-way ANOVA with Dunnett's multiple comparisons test was applied to compare each aAPC to Clone 4. (B) NK cells from four additional donors stimulated weekly for 21 days prior to assessing telomere length, and again normalized to that of fresh cells from each donor. P value shown for two-tailed t-test.