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Lookup NU author(s): Dr Alexei von Delwig, Professor John IsaacsORCiD, Professor John Robinson
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RATIONALE: We are investigating the mechanisms of intracellular antigen processing of human type II collagen (CII) for presentation of the arthritogenic epitope CII259-274 to specific CD4 T cells in DR1-transgenic mice (DR1-tg, C57BL/6J0-0 DR1), as a model for rheumatoid arthritis. METHODS: DR1-tg mice were immunized with CII emulsified in Complete Freund’s adjuvant, and the development of collagen-induced arthritis was monitored for 6-8 weeks. Bone-marrow macrophages were used as APC and we have generated T cell lines and hybridomas specific for CII259–274 [GIAGFKGEQGPKGEB] to quantitate Ag presentation of the arthritogenic epitope. Subcellular fraction of macrophages was used as a source of enzyme activity for cell-free Ag processing in the presence and absence enzyme inhibitors to localize stages of CII degradation to particular endosomal/lysosomal compartments and identify the families of enzymes involved. RESULTS: We have shown that this new DR1-tg murine MHC class II knock out substrain of mice are susceptible to collagen-induced arthritis. In whole cell Ag presentation assays bone marrow macrophages from DR1-tg mice process intact CII for presentation of the arthritogenic epitope CII259–274 to T cell hybridomas. Subcellular fractionation of macrophages localized CII degradation to fractions containing lysosomes. CII digestion occurred over the pH range 4.5 to 6.5 giving rise to at least seven identifiable cleavage fragments with molecular mass 50-100 kDa. CII cleavage by lysosomal fractions was prevented by inhibitors of serine and cysteine proteinases. CONCLUSIONS: We have shown that CII is degraded by lysosome-rich subcellular fractions from macrophages. CII processing was dependent on serine and cysteine proteinase activity. We are now investigating which of the digestion products are presented to CII259-274 -specific DR1-restricted T cells. An understanding of the mechanisms of antigen processing of CII may reveal why arthritogenic epitopes activate autoreactive T cells during the initiation of collagen-induced arthritis.
Author(s): Delwig vonA; Isaacs JD; Robinson JH; Altmann DM; McKie N
Publication type: Conference Proceedings (inc. Abstract)
Publication status: Published
Conference Name: 12th International Congress of Immunology
Year of Conference: 2004
Notes: Published in 'Clinical and Investigative Medicine' (CIM), 2004, 27 (4), page 42A
