As MARCO is considered to be expressed on both macrophages and dendritic cells (DCs), we next examined the localization of MARCO and the following markers of macrophages and DCs: CD68 as a marker of both M1 and M2 macrophages; CD163 as a marker of M2 macrophages; CD11c as a marker of myeloid DCs; CD123 as a marker of plasmacytoid DCs; and CD21 as a marker of follicular DCs, in SMG from patients with IgG4-RD. Here, MARCO is linked to immunoglobulin G4-related sclerosing disease.