IL5 and immunoglobulin G4-related sclerosing disease: mAbs targeting IL-5 (e.g., mepolizumab and reslizumab) or the IL-5 receptor (IL-5R) (e.g., benralizumab) reduce peripheral eosinophilia (145) and therefore might be effective therapies in IgG4-RD patients with peripheral or tissue eosinophilia.