Functional annotation of biological processes revealed that proteins highly expressed in the mild BD group were enriched in immune response (C1QA, ECM1, IGHV1‐3, TUBB, APOA2, IGHV2‐26, IGKV1D‐33, IGHV1‐18, C3, IGLL5, IGLV1‐51, ADAMTS13, IGKV1‐27, IGLV6‐57, CFHR4, C1RL, LCP1, A2M, PF4, LTF), protein activation cascade (C3, C1QA, CFHR4, FGG, C1RL, FBLN1, A2M), and immune effector response (C3, C1QA, IGLL5, IGHV1‐3, CFHR4, TUBB, C1RL, APOA2, LCP1, IGHV2‐26, A2M, IGHV1‐18). Here, A2M is linked to Behcet disease.