CCL21 and hematocrit: Interestingly, we found many CCL21+ fibroblasts were distributed in the TC zones of TLOs in thyroid tissues from HT patients (Fig. 5d–f), suggesting that CCL21+ fibroblasts (F1) in TC zones of TLOs could be a counterpart of lymphoid tissue organizer cells, to promote lymphocytes recruitment and the formation of TLOs in thyroid tissues of HT patients.