With antiIL18R antibody treatment, the percent of CD83+CCR7+NK cells (Figure5B) and expression (Figure5C) and secretion (Figure5D) of IFN in NK cells were all decreased as compared with those nontreated or IgGtreatedNK cell. tissue damage, as well as the number of infiltrating CD83+CCR7+NK cells, T cells Arhalofenate and DCs in the inflamed eyes and spleens of EAU mice. These results suggest that CD83+CCR7+NK cells, as induced by IL18 that primarily secreted by DCs, play a critical pathological role in EAU. Arhalofenate AntiIL18R antibody might serve as a potential therapeutic agent for uveitis through its capacity to inhibit CD83+CCR7+NK cells infiltration. Keywords:autoimmune uveitis, dendritic cells, IL18, natural killer cells == 1. INTRODUCTION == Uveitis, an inflammatory disease involving the uvea, retina, retinal vessels and/or vitreous body, can result in visual impairment and blindness.1This condition encompasses a variety of intraocular inflammations which can affect the anterior, middle, or posterior regions of the eye.1,2If uveitis is localized to the posterior region, it can affect photoreceptor cells and will likely lead to a visual disability.1,2A disorder of the immune system represents an essential pathogenesis for autoimmunity uveitis. In specific, the large number of lymphocytes, including mature dendritic cells Arhalofenate (DCs), T cells and natural killer (NK) cells infiltrating the eye may be a critical factor which drives this disorder of the immune system to result in tissue damage.1,2,3,4,5,6However, the underlying mechanisms of uveitis remain unclear. Recently, NK cells have been reported to play a role in experimental autoimmune uveitis (EAU).3,4,6,7,8NK cells, which are a component of the innate immune system, represent the first line of defence against infections and play a regulatory role in autoimmune diseases by regulating the secretion of cytokines or by interacting with other cells.9,10,11,12,13,14,15As activated NK cells produce a significant increase in the expression of IFN in Behcets disease, a type of autoimmune uveitis,4,6any prevention in the secretion of IFN from NK cells would have the potential to alleviate uveitis. An alteration in the status of NK cells may also contribute to the recovery of Behcets disease through suppression of Th1 responses,4,6which represents a pathogenic factor for uveitis.6,16,17,18,19Depleting of NK cells would alleviate the symptom of EAU.8Thus, the status of NK cells plays a critical role with regard to the development of autoimmune uveitis. Previous findings from our laboratory have revealed that EAU increased the number of CD3NK1. 1+NK cells during its inflammatory stages within the eyes and spleens.3Moreover, these cells expressed increased levels of CD83 and secreted elevated levels of IFN.3However, the role of such CD83+NK cells in EAU remains unknown and the specific factors affecting activation of NK cells in uveitis are unclear. Interleukin18 is a proinflammatory cytokine and is originally defined as an IFNinducingfactor.20It has been reported that IL18 promotes differentiation of the NK cell specifically, CD56+/CD83+/CCR7+cells, as well as the migration of NK cells.21However, whether IL18 promotes NK cell activation in uveitis is unknown. IL18 is constitutively produced by haematopoietic cells, such as DCs, macrophages and neutrophils,22,23,24as well as in nonhematopoietic cells, such as microglial and epithelial cells.25IL18 involves binding with its receptor, consisting of IL18R1 and IL18R accessory protein in a heterodimeric receptor complex, to initiate signal transduction by the myeloid differentiation primary response protein 88 (MyD88). The nuclear factor (NF) kappalightchainenhancer of activated B cells (B) and mitogenactivated protein kinase pathways (MAPK pathways) are then activated, which promote IFN transcription and stabilization of IFNG mRNA.26,27,28Recently, the role of IL18 in uveitis has attracted considerable attention as it has been shown in both clinical and EAU models, that IL18 shows enhanced expression during the inflammatory phase of the disease,29,30,31,32,33,34and polymorphism of the IL18 gene is closely related to the occurrence of uveitis.35,36Thus, these reports indicate that IL18 might participate in the inflammation of EAU. However, the mechanisms of IL18 in uveitis remain unknown. In this report, we investigated the status of NK cells and their role in uveitis, and tested the capacity for IL18 to influence NK cell RAC status in uveitis. And then, the possible cell subsets involved in Arhalofenate secreting IL18 in uveitis were measured. In addition, we examined whether blocking of IL18 receptor would alleviate the development of uveitis and affect the status of CD83+CCR7+NK cells, DCs and T cells. The increases in IL18 observed in EAU might represent an important factor which promotes CD83+CCR7+NK cell activation, thereby participating in the development of uveitis. == 2. MATERIALS AND METHODS == == 2.1. Experimental autoimmune uveitis == Pathogenfree female C57BL/6 (B6) mice Arhalofenate (68 weeks of age) were purchased from the Peking Vital River Laboratory Animal Ltd.,.