C4A and interstitial lung disease: And it had no correlation with such clinical features including sex, disease duration (month), ocular dryness, tooth damage, dry skin, fatigue, purpura, joint pain, lymph node enlargement, Raynod's phenomenon, morning stiffness, WBC, NEUT, LYM, PLT, CRP, IL-6, IgG, C3, C4, RF, AbSSA(52), AbSSA(60), AbSSB, ESSDAI, antinuclear antibody titer, combined hypertension, coronary heart disease, hyperlipidemia, hyperuricemia, fatty liver, interstitial lung disease, chronic gastritis (Table 3).