This is further supported by previous studies that described elevated sIL-2R levels in IgG4-RD, especially in relation to the higher percentage (>40%) of IgG4-positive plasma cells in the salivary gland tissues [22], glycolysis within the tissues [26], and increased levels of CC-chemokine ligand 18 (CCL18), a substantial marker for fibrotic diseases [27]. This evidence concerns the gene CCL18 and immunoglobulin G4-related sclerosing disease.