A sub-analysis of CCR6+ CD4+ T cells, identifying CXCR3-CCR4+ Th17, CXCR3+CCR4- Th17.1, CXCR3+CCR4+ double positive (DP) and CXCR3-CCR4- double negative (DN) cells, showed a particularly strong increase in the proportions of CXCR3-CCR4- DN T cells in CTEPH patients compared to HCs (Supplementary Figures 2A, B). Here, CCR6 is linked to chronic thromboembolic pulmonary hypertension.