The present application provides compositions and methods for detecting andmonitoringautoimmune diseases in a human subject. The compositions comprise a moesinfragment forbinding to an anti-moesin autoantibody and a buffer. The moesin fragmentcomprises at least tenconsecutive amino acid residues from the N-terminal FERM (band four-point-one,ezrin, radixin,moesin homology) domain of a human moesin protein. The human subject has or issuspected ofhaving an autoimmune disease that is connective tissue disease (CTD), systemicsclerosis,Sjogren's syndrome, or systemic lupus erythematosus.
