IgG4-assoziierte Autoimmunerkrankungen

Abstract

Immunoglobulin G4-related diseases (IgG4-RD) are rare autoimmune diseases, which as multisystemic diseases can also affect several organs simultaneously. The symptoms can be very different depending on the organ affected. The diagnosis of IgG4-RD is based on the presence of typical organ swelling and/or fibrosis of the affected organ, corresponding clinical symptoms, serological alterations with elevated serum concentrations of IgG4 (≥ 135 mg/dl) and a pathognomonic histopathology with predominant lymphocellular infiltration and a high proportion of IgG4 positive plasma cells (> 10 plasma cells/high-power field, HPF; IgG4/IgG positive plasma cells ≥ 40%). For the diagnostics of IgG4-RD in general as well as for specific organ manifestations, such as IgG4-associated autoimmune pancreatitis (IgG4-AIP) and IgG4-associated cholangitis (IAC) organ-specific criteria and scores have been developed. As the diagnostic gold standard histopathological confirmation should be strived for. After diagnosis of an IgG4-RD immunosuppressive treatment should be carried out. The standard treatment consists of corticosteroid treatment as induction phase and low-dosed for recurrence prophylaxis as maintenance treatment for 1 year. Recurrent exacerbations of IgG4-RD can lead to organ fibrosis with subsequent loss of function of the affected organ. In cases of contraindications to steroid treatment or a steroid-refractory course, treatment with azathioprine or rituximab can be considered.