This invention relates to a peptide comprising or consisting of at least 8 consecutive amino acid residues of the sequence set forth in SEQ ID NO: 3, provided that said peptide does not consist of the sequence set forth in SEQ ID NO: 3, or a corresponding peptidomimetic, wherein said peptide or peptidomimetic binds to an anti-KIR4.1 antibody comprised in a sample from a patient, said patient having multiple sclerosis or a predisposition therefor, wherein preferably (i) said at least 8 consecutive amino acid residues are a subsequence of an extracellular domain of KIR4.1, said extracellular domain consisting of the sequence set forth in SEQ ID NO: 1 or 2； or (ii) said peptide comprises or consists of the sequence of SEQ ID NO: 1 or 2. The present invention furthermore relates to a method for diagnosing multiple sclerosis or a predisposition for multiple sclerosis in a subject, the method comprising determining the presence of an anti-KIR4.1 antibody in a sample obtained from said subject, wherein the presence of an anti-KIR4.1 antibody in said sample is indicative of multiple sclerosis or a predisposition for multiple sclerosis. Also provided are novel means and methods for the therapy of multiple sclerosis.
