In the course of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis, autoreactive T cells that have been activated in peripheral lymphoid tissue need to be reactivated within the central nervous system. So far, no knowledge about the peptide fragments presented on MHC class I and class II molecules within the central nervous system have been obtained. In preliminary experiments we have eluted peptides from MHC class II molecules of DA rats with EAE and controls after central nervous system dissection an affinity chromatography. Mass spectrometry analysis of eluted peptides from the MHC class II RT1.Ba (HLA-DQ-like) molecule resulted in the identification of central nervous system specific peptides. In the planned studies we will analyze additional eluted peptides of RT1.A (MHC class I) and RT1.D (MHC class II, HLA-DRlike) molecules. Subsequently, we will analyze the immunogenicity and encephalitogenicity of these peptides by immunization of DA rats with the eluted peptides. In order to get relevant information about naturally presented peptides in the context of human MHC class II molecules we will perform similar studies in HLA-DR2b transgenic mice. The identified naturally processed central nervous system peptides will be subsequently analyzed for T and B cell reactivity in patients with multiple sclerosis and controls by ELISPOT and on a functional level by FACS and quantitative PCR. We hope that our study will reveal important information regarding the presentation of peptides involved in CNS autoimmunity.
