Withdraw Drug in Stable IgG4-Related Disease

Inclusion Criteria: 1. All patients must meet the following diagnostic criteria of IgG4RD (2011): 1)Swelling, sclerosing and inflammatory involvement of one or more organ, including sclerosing pancreatitis, sialadenitis (Mikulicz disease), sclerosing cholangitis, inflammatory pseudotumors, retroperitoneal or mediastinal fibrosis, interstitial nephritis, hypophysitis, sclerosing dacryoadenitis, inflammatory aortic aneurysm, lymphadenopathy, or other inflammatory conditions; 2)Elevated serum IgG4 (\>1.35 g/L); 3)Histopathologic features of fibrosis and/or lymphocytic and polyclonal plasma cell infiltration (and IgG4+ plasma cells on immunohistology when performed). Patients fulfill 1)+2)+3) are diagnosed as definite IgD4RD, 1)+2): possible IgG4RD; 1)+3): probable IgG4RD. exclusion of other diseases. 2. Disease stabilized more than one year (Responder Index \< 2 points) 3. Dose of Glucocorticoid(GC): prednisone (or equivalent) ≤ 7.5mg/d for more than 6 months 4. Immunosuppressant: one of the following drugs, the same dose maintain at least 3 months (Mycophenolate mate \<= 1g/d or Leflunomide \<=20mg/d or Methotrexate \<=12.5mg/w or Azathioprine \<=100mg/d). Exclusion Criteria: 1. Patient was diagnosed other connective tissue diseases 2. Patient with tumor 3. Women during pregnancy or planning pregnancy 4. Patient with active infections, including HIV, HCV, HBV, TB, etc. 5. Patient with severe irreversible organ damage 6. Active IgG4-RD, responder index \>= 2 points 7. Stable condition less than one year. 8. Patient with two or more immunosuppressive agents. 9. Biological agents (such as CD20 monoclonal antibody and TNF-a inhibitor) have been used for half a year before admission. 10. Patient with IgG4-RD recurrence during hormone reduction in the past.