Abstract: The present invention provides a chimeric polypeptide receptor in which an extracellular region comprising an antigenic region capable of being bound by an anti-human nicotinic acetylcholine receptor ?1 subunit (nAChR?1) antibody, a transmembrane region, and an intracellular domain comprising an intracellular signaling domain are arranged in the presented order from the N-terminus towards the C-terminus, wherein an amino acid sequence of the antigenic region comprises the amino acid sequence as set forth in SEQ ID NO: 2 or an amino acid sequence derived from the amino acid sequence as set forth in SEQ ID NO: 2 by the substitution, deletion, insertion, and/or addition of one or several amino acids, a polynucleotide encoding the chimeric polypeptide receptor polypeptide, a cell expressing the chimeric polypeptide receptor, etc., which are useful in the treatment of myasthenia gravis.

Abstract: The present invention provides an antibody that recognizes a polypeptide comprising the amino acid sequence represented by SEQ ID NO: 15 in the Sequence Listing and has an anti-arthritic function, or a functional fragment thereof.