Increased plasma levels of TGF-β and TSLP correlate with the increased percentage of CD207 expressing cells in patients with active LCH. (A-B) Plasma levels of TGF-β and TSLP were measured by enzyme-linked immunosorbent assay, and independent data from patients with NAD (N = 12) and AD (N = 9) are graphed. (C-D) Plasma levels of TGF-β and TSLP correlated with the percentage of monocytes (CD11b^highCD11c⁺) expressing CD207 (CD207⁺ plus CD207⁺CD1a⁺) (Spearman test). (E-F) CD14⁺ monocytes were isolated from healthy volunteers and cultured in the presence of plasma from patients with AD or NAD (10% vol/vol) for 4 to 10 days. CD207 and CD1a expression was evaluated in CD11c⁺CD11b^low cells by flow cytometry. (E) Representative dot plot of CD207 vs CD1a at day 10. GM-CSF, IL-4, and TGF-β were used as positive controls (see also supplemental Figure 3A). (F) Kinetic expression of CD207 at days 4, 7, and 10. Significant differences between patients with NAD and AD were calculated using a Student t test (*P < .05; **P < .01; ***P < .001).