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Immunoglobulin G4-related Disease: What an Allergist Should Know

Carballo I1, González-Quintela A1,2, Sopeña B1, Vidal C2,3

1Department of Internal Medicine, Complejo Hospitalario Universitario de Santiago, University of Santiago de Compostela, Santiago de Compostela, Spain
2Spanish Network for Addictive Disorders (Red de Trastornos Adictivos, RD16/0017/0018), Spain
3Department of Allergy, Complejo Hospitalario Universitario de Santiago, University of Santiago de Compostela, Santiago de Compostela, Spain

J Investig Allergol Clin Immunol 2021; Vol. 31(3)
doi: 10.18176/jiaci.0633

Immunoglobulin G4 related disease (IgG4 RD) is a fibroinflammatory disorder that begins in one or more organs as inflammatory tumours that evolve toward fibrosis and is often accompanied by elevated serum IgG4. It was first described in 2003 as a new concept that encompasses a number of diseases, immune allergic in nature, previously considered unrelated. IgG4 RD mainly affects middle aged and older men. It consists of an up regulated and expansion of CD4+ cytotoxic T lymphocytes , oligoclonalplasmablasts and other inflammatory cells that infiltrate affected tissues and induce inflammation, organ dysfunction, and fibrosis. Symptoms depend on the location, severity and extent of the disease. Any organ can virtually be affected: pancreas, salivary and lacrimal glands, thyroid gland, retrorbital tissue, lymph nodes, retroperitoneum, mediastinum, lung, kidney, aorta, serosal surfaces, and meninges. Patients with widespread disease may present general symptoms. At least 30-40% patients are atopic or display atopy traits such as eosinophilia or elevated serum IgE levels . Additional laboratory features can include increased serum IgG4 concentrations, increased blood IgG4 plasmablasts, hypergammaglobulinemia, and hypocomplementemia. Diagnosis of IgG4 RD is based on a clinical pathological correlation. Lymphoplasmacytic infiltrate with abundant IgG4 positive plasma cells, storiform type fibrosis, obliterative phlebitis, and tissue eosinophilia are the pathological hallmarks.Therapy for IgG4 RD is primarily based on corticosteroids but may include additional immunomodulatory drugs and monoclonal antibodies such as rituximab In individuals with allergy features, IgG4 RD should be suspected when a history of unexplained swelling in one or more organ is present particularly if they respond to corticosteroids and are males over the 6th decade of life.

Key words: Immunoglobulin G4-Related Disease, Allergy, Immunoglobulin G, IgG4, Immunoglobulin E, Eosinophils, Inflammation, Fibrosis