To solve the enigma regarding allergic reactions, eosinophilia and hyper-IgE levels in IgG4-RD, some authors have revealed that IL-10 can suppress allergen-specific accessory function of monocytes and Th2 responses, thereby decrease the IL-4-induced IgE synthesis [91,92,93]. Here, IL10 is linked to immunoglobulin G4-related sclerosing disease.