Increased IL-7 expression in Vogt-Koyanagi-Harada disease.

PURPOSE: IL-7/IL-7R has been found to be involved in the pathogenesis of several autoimmune diseases. This study was designed to investigate the potential role of IL-7/IL-7R in the pathogenesis of Vogt Koyanagi-Harada (VKH), an organ-specific autoimmune disease. METHODS: IL-7 was measured with an enzyme-linked immunosorbent assay (ELISA) in serum obtained from patients with active or inactive VKH and from healthy individuals. The expression of IL-7R was measured by flow cytometry (FCM). Cell proliferation was determined after exposure of peripheral blood mononuclear cells (PBMCs) and CD4(+) T cells to recombinant IL-7. The levels of IL-17 and IFN-γ levels were detected by ELISA after these cells were cocultured with recombinant IL-7. The influence of recombinant IL-7 on the expansion of Th1 and Th17 cells was evaluated by using FCM. RESULTS: IL-7 was significantly increased in the serum of patients with active VKH compared with those with inactive VKH (P < 0.001) and normal controls (P < 0.001). However, there was no difference between VKH patients and normal controls in the expression of IL-7Rα on CD4(+) T cells. Recombinant IL-7 induced significant cell proliferation and secretion of IL-17 and IFN-γ by PBMCs and CD4(+) T cells. It furthermore promoted the expansion of both Th1 and Th17 cells. CONCLUSIONS: The findings suggest that IL-7 is involved in the pathogenesis of VKH disease.