C3 and systemic lupus erythematosus: They found differentiating levels of 14 complement pathway proteins – 8 were upregulated (C3, C4b, C5, C7, C8 alpha subunit, C8 gamma subunit, vitronectin, CFH) and 6 were downregulated (mannose-binding lectin serine protease-2, C6, CFD, and VSIG-4) in active SLE.