We performed surface staining of freshly frozen PBMC from CTOT-09 study as previously published.25 (link) Anti-human antibodies included: FITC-anti-CD127 (clone: A019D5; Biolegend), PE-anti-CD3 (clone: UCHT1; BD Bioscience), PerCP-Cy5.5-anti-CD57 (clone: HNK-1; Biolegend), PE-Cy7-anti-CD4 (clone: RPA-T4; eBioscience), APC-anti-CD25 (clone: 4E3; Miltenyi Biotec), APC-Cy7-anti-PD-1 (clone EH12.2H7; Biolegend), and BV510-anti-CD8 (clone: RPA-T8; BD Biosciences). Data were acquired (> 1 × 106 events) on a 3-laser FACSLyric flow cytometer (BD Biosciences) and analyzed using FlowJo software.