Abstract
Abstract: :
Purpose: Uveitis is an inflammatory autoimmune disease of the eye, mediated by CD4-positive T cells specific for ocular antigens. In Lewis rats EAU can be induced by adoptive transfer of T cell lines specific for retinal antigens. Due to its clear optical media the eye allows observation of autoreactive lymphocytes in EAU without surgical intervention, by using the cornea as a natural window. Methods: T cells retrovirally engineered for the expression of green fluorescent protein (GFP) and specific for retinal peptide PDSAg (S-Ag-peptide) or OVA were injected intravenously into naive animals and followed by intravital microscopy of iris and anterior chamber. Intravital microscopy of anaesthesized rats was performed at various time points. Experiments were terminated 4-7 days later, and the eyes and spleens processed for histology and FACS-analysis. Results: As early as 3 hours after injection OVA-specific as well as PDSAg-specific T cells extravasate into the stroma of the iris to a similar extent. Nevertheless, clinical signs of uveitis such as precipitation of leukocytes on iris tissue and anterior chamber could only be detected 3-4 days later in those animals that had received PDSAg-specific T cells. After clinical onset of disease only few GFP-positive T cells were observed in the eye, while more than 90% of inflammatory cells were negative for GFP. On FACS-analysis activation makers such as OX-40 and IL-2-receptor were upregulated on GFP-positive cells in eyes, but not in the spleen, indicating a reactivation of retinal antigen specific T cells within the eye. Conclusion: The immigration of antigen specific T cells as an initial event precedes the clinical signs of disease by several days. The majority of immune cells causing inflammation and destruction within the eye is unspecifically recruited from the recipient´s immune system.
Keywords: 327 autoimmune disease • 612 uveitis-clinical/animal model