T cell responses to a non-glycosylated epitope predominate in type II collagen-immunised HLA-DRB1*0101 transgenic mice.

Aim: To study collagen-induced arthritis in human leucocyte antigen (HLA)-DR1 transgenic mice lacking endogenous major histocompatibility complex class II molecules (MHC-II) and to determine T cell specificity against the arthritogenic CII 259–273 epitope of type II collagen either unmodified or post-translationally glycosylated at Lys 264 . Methods: Arthritis was induced by immunisation with human type II collagen in complete Freund’s adjuvant and measured by footpad swelling, clinical score and histology. T cell responses were assessed by proliferation of spleen and lymph node cells and in antigen presentation assays, using T cell hybridomas specific for the glycosylated and non-glycosylated CII 259–273 epitope. Results: The incidence of arthritis was 50% in DR1-transgenic mice lacking endogenous MHC-II molecules. Recall T cell responses in draining lymph nodes and spleen were consistently greater against the non-glycosylated epitope than to the glycosylated CII 259–273 . Most of the T cell hybridomas generated from CII-immunised mice recognised the non-glycosylated CII epitope and this form of the epitope was also presented with 100-fold higher efficiency and 1 h faster kinetics by both macrophages and dendritic cells. Conclusion: This study shows that T cell responses to the non-glycosylated epitope of heterologous (human) CII are dominant in HLA-DR1 transgenic mice lacking MHC-II, which could contribute to the pathogenicity of autoimmune arthritis.