Abstract: A protein consisting essentially of purified oligodendrocyte-specific protein or purified biologically active variants thereof, or a combination of purified oligodendrocyte-specific protein and biologically active variants thereof. A purified and isolated peptide having the sequence Ala-Lys-Tyr-Arg-Arg-Ala-Gln-Leu-Ala-Gly residues 115-124 of SEQ ID NO:2. A device for identifying an epitope region of a peptide, protein, or protein homologue of interest comprising a polypropylene membrane having a plurality of sequentially oriented peptide spots, each spot containing a peptide having an amino acid sequence where the amino acid sequences of the peptides on the peptide spots sequentially progress through the amino acid sequence of the peptide, protein, or protein homologue of interest. A method of diagnosing multiple sclerosis and a method of treating multiple sclerosis.