No abstract

Finally, to determine whether buffer E would preserve the RNA of PBMCs over time, we analyzed total RNA obtained from 8 individuals at t 3 , t 5 , t 10 , and t 15 of PBMC storage time with reference to their t 0 values. For all samples examined, RNA purity, determined by the A 260 / A 280 ratio, was 1.8 -2.1, indicating that highly pure RNA could be obtained with storage in buffer E. In addition, for all 3 genes, we observed no significant variations in either the amount (Fig. 1C; Friedman test, P ϭ 0.0812) or the integrity (Fig. 1C of the online Data Supplement; Friedman test, P ϭ 0.3682) of RNA at t 3 , t 5 , t 10 , and t 15 compared with t 0 . Thus, buffer E provides advantageous conditions for PBMC storage at Ϫ80°C. In addition, it is noteworthy that buffer E is also suitable for manual extraction (see the manufacturer's instructions), which does not necessarily require specific and costly automation.