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JM Liversidge, A Dick, C Calder, J Sedgwick, N Taylor; Role of Myeloid Regulatory Molecule CD200 in Tolerance Induction Via the Nasal Mucosa . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1544.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:A myeloid regulatory role for CD200 has been proposed since disruption of signalling via CD200R in animal models leads to an accumulation of DAP-12+ F4/80+ cells within normal lymphoid and non-lymphoid tissues predisposing the animal to autoimmune inflammation. The purpose of this study was to examine the phenotype and function of CD200-/- (KO) macrophages and dendritic cells compared to CD200+/+ (WT) in the context of tolerance induction to EAU via the nasal mucosa. Methods:Respiratory tract myeloid cells (RTMC), draining cervical lymph nodes (CLN), submandibular lymph nodes (SMLN) and spleens (SPL), from CD200 WT or KO C57Bl/6 mice were examined by FACSs analysis and immunocytochemistry at time zero (control) or at intervals following instillation of IRBP peptide 1-20 ( 50ug) or PBS intranasally (minimum of 3 animals at each time point). Groups of 4 WT or KO animals were tolerised using 50mg peptide 1-20 or control PBS and then challenged 10 days later by immunisation with 500ug peptide 1-20 in FCS with pertussis toxin as additional adjuvant. Control mice were challenged with PBS in FCS. Eyes were taken at day 16 post immunisation and scored for retinal damage. Results:FACS analysis of RTMC indicated that cells were of an immature APC phenotype and expressed lower levels of MHC class II than WT. Significant reductions in MHC Class II+ expression by both dendritic cells and macrophages in lymphoid tissue from KO mice were also found. Image analysis of immunostained sections of lymphoid tissue sampled from animals at 0-48h post intranasal challenge with peptide 1-20 confirmed this and that low MHC class II expression by KO cells persisted for up to 48h. STAT-4 expression by both WT and KO lymphoid cells was generally weak, although a few strongly positive cells were observed at 24-48 hours. In contrast, STAT 6 was strongly expressed particularly by WT cells and was increased over time with strongest expression in T cell areas of CLN at 4h-48h. Conclusion:Although the DAP-12 activated phenotype of myeloid cells from CD200-/- mice pre-disposes these animals to autoimmunity the activation phenotype does not appear to extend to MHC class II expression or dominant expression of Th1 signalling STAT4 protein in our model. However, dominant expression of STAT6 Th2 signalling protein may contribute to the low levels of EAU pathology in the C57/Bl6 mouse and the reduced MHC class II expression that we observed.
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