library_construction_protocol: ATAC-seq: nuclei were isolated from 100,000 PBMCs by incubation in 50 µl lysis buffer (10 mM Tris-HCl, pH 8.0; 10 mM NaCl; 3 mM MgCl₂; 0.1% Tween-20; 0.1% IGEPAL CA-630; 0.01% digitonin). After 3 minutes on ice, 1 ml wash buffer (10 mM Tris-HCl, pH 8.0; 10 mM NaCl; 3 mM MgCl₂; 0.1% Tween-20) was added. Nuclei were pelleted and subjected to transposition using a Tn5 transposase reaction mix (Illumina), supplemented with 0.01% digitonin and 0.1% Tween-20. The transposition reaction was carried out at 37 °C for 30 minutes in a thermomixer. Transposed DNA was purified using the DNA Clean & Concentrator-5 Kit (Zymo Research), followed by PCR amplification, purification, and size selection with SPRISelect beads (Beckman Coulter). Library quality was assessed using an Agilent TapeStation. Indexed libraries were quantified, pooled, and prepared for sequencing. ATAC-seq  libraries were sequenced on an Illumina NextSeq500 system (Illumina) at 75 bp read length using standard protocols at the Gene Core facility of the EMBL (Heidelberg, Germany).