In the moderate BD group, highly expressed proteins were primarily involved in defense response (CRP, ORM1, CFH, C1S, RARRES2, CFI, MST1, KRT1, SAA4, HP, TNC, HPR, IFNW1, KNG1, LOC102723996, C9, SAA1, LBP, APOL1, CFB), acute‐phase response (CRP, ORM1, SAA4, SAA1, HP, HPR, LBP), and immune response (CRP, IGHV3‐43D, CFH, C1S, IGHV3‐11, RARRES2, CFI, MST1, KRT1, IFNW1, ICAM1, VTN, AZGP1, LOC102723996, C9, IGHD, ENPP2, LBP, APOL1, CFB). Here, C1S is linked to Behcet disease.