IGHE and immunoglobulin G4-related sclerosing disease: At baseline, the serum IgE level was positively correlated with the serum IgG4 level (r = 0.1779, P = 0.0001), eosinophil count (r = 0.3004, P < 0.0001), and serum IgG level (r = 0.2189, P < 0.0001) in IgG4-RD patients.