Expression of Interleukin-17 in Autoimmune Dacryoadenitis in MRL/lpr Mice

Purpose: Th-cytokines play important roles in dacryoadenitis associated with Sjogren's syndrome (SS). The aims of this study were to (i) investigate whether interleukin (IL)-17, a newly identified Th-cytokine, participates in autoimmune dacryoadenitis of MRL/lpr mice and (ii) examine the relationships among IL-17, IL-4, and interferon (IFN)-gamma in these mice. Methods: Three-month-old MRL/lpr mice with lacrimal gland inflammation and 3-month-old control BALB/c mice were used. Frozen sections of lacrimal glands and submandibular lymph nodes were stained with monoclonal antibodies to cytokines IL-17, IL-4, and IFN-gamma. Concentrations of IL-17 in serum and 48-h splenocyte culture supernatants were detected by ELISA. Results: Marked lacrimal gland inflammation was observed in all MRL/lpr mice but not in any BALB/c control mice. In the lacrimal glands of MRL/lpr mice, the proportions of cells that stained were 5 +/- 3% for IL-17, 32 +/- 14% for IL-4, and 4 +/- 2% for IFN-gamma. In the submandibular lymph nodes of MRL/lpr mice, expression of IL-17 and IL-4 was significantly higher than that of IFN-gamma, and all three cytokines were significantly higher in MRL/lpr mice than in BALB/c mice. Concentrations of IL-17 in both serum and splenocyte culture supernatants of MRL/lpr mice were elevated compared to BALB/c controls. Conclusions: Since expression of IL-17 is elevated in 3-month-old MRL/lpr mice, we suggest that it plays a role in the pathophysiology of autoimmune dacryoadenitis in these mice.