C4A and interstitial lung disease: The baseline clinical data showed that the pSS–MN patients had significantly higher WBC, LY, NE, PLT, CR, C3, UAER, SSA, Ro52, PRO, UOB, and ILD and lower ALB, γ-globulin, IgG, C4, and RF than SS patients (all P < 0.05) (Table 1).