DNA from 50,000 CD4+ T-cells was prepared as previously described by others (Buenrostro, J.D., Wu, B., Chang, H.Y., and Greenleaf, W.J. (2015). ATAC-seq: A Method for Assaying Chromatin Accessibility Genome-Wide. Curr Protoc Mol Biol 109, 21.29.21-29.) Briefly, cells were lysed and the nuclei underwent the transposition reaction at 37oC for 30 minutes. DNA was purified after transposition reaction using Qiagen MinElute PCR Purification Kit and libraries were generated by amplifying DNA with 12-15 cycles. Necessary cycles determined by qPCR. DNA was purified using AMPure XP beads, quality and quantity was determined by Agilent bioanalyzer (high sensitivity DNA kit), and the libraries were subsequently sequenced.