CD4+ T cells were cultured under Th17 cell polarizing conditions for 72h. Chromatin was prepared (Diagenode Chromatin shearing optimization kit) and further subjected to sonication (Bioruptor, Diagenode) to obtain chromatin fragments of 100–500 bps. Histone DNA complexes were isolated using antibodies against FOSL1, FOSL2 or BATF. Libraries were prepared according to Illumina's instructions.