Objective:To seek candidate autoantigens in circulating immune complexes(CICs)in dermatomyositis and polymyositis(DM/PM),analyze autoantigens through Orbitrap mass spectrometry,to assist in the early diagnosis of DM/PM.Methods:CICs from the serum of three DM patients and three healthy controls were collected using Protein A/G beads.Subsequently,the enriched proteins were eluted from the column and separated on SDS-PAGE,then digested with trypsin.The digested products were labeled with the TMT 6-plex reagents.The labeled products were desalted by a C18 stage tip column and subjected to Orbitrap mass spectrometry for identifying and profiling antigens in CICs.Differential expressed proteins were screened by fold change(DM/HC≥1.5 and credibility score≥10 points).