Differences in the pathogenesis of Mikulicz's disease and Sjögren's syndrome

Objectives:Because of the histopathologic similarities between Mikulicz's disease (MD) and Sjögren's syndrome (SS), MD has been considered to be a subtype of SS. However, recent studies have indicated that MD shows high serum IgG4 concentration, and suggested that MD is a distinguishable disease from SS. In addition, autoimmune pancreatitis associated with MD has been reported to show the infiltration of not only IgG4+ B cell but also Treg in pancreatic tissue. Therefore, we examined the disease states in detail of MD and SS.

Methods:Ten patients with MD and 18 patients with SS referred to Kyushu University Hospital between April 1993 and July 2007 were included in the study. The clinical findings such as mainly the serologic findings were examined. In addition, subsets of the infiltrating lymphocytes and the expression of Th1/Th2 and Treg types cytokines, chemokines and chemokine receptors in the SG were examined by an immunological analysis.

Results:The serologic findings in SS patients were the following: high serum IgG concentration, 69%; positive rate of ANA, 100%; anti SS-A antibodies, 88%; and anti SS-B antibodies, 50%. On the other hand, in MD patients: high serum IgG concentration, 90%; positive rate of ANA, 40%; anti SS-A antibodies, 0%; and anti SS-B antibodies, 0%. Furthermore, high serum IgG4 concentration was observed in the searchable MD patients. As concerns the SG, SS showed the lymphocytes infiltration of various subsets and the increased expression of both Th1 and Th2 types molecules, whereas MD showed the selective IgG4+ B cell and Treg infiltration and the increased expression of Th2 and Treg types molecules.

Conclusions:These results suggest that the pathogenesis of MD is clearly different from that of SS, and that MD might not be s subtype of SS but independent disease.