IgG4+ Plasma Cells in Gastric Biopsies Specific for Patients with Autoimmune Atrophic Gastritis/Pernicious Anemia
AS Bedeir, JG Lash, MB Ray. Caris Diagnostics, Irving, TX
Background: Although initially described in autoimmune pancreatitis, the presence of increased IgG4 + plasma cells has also been noted in other autoimmune diseases and other organs. Autoimmune gastritis is characterized by anti-parietal and anti-intrinsic factor antibodies that can cause pernicious anemia (PA). Histologically, autoimmune gastritis manifests as a chronic atrophic gastritis (CATG) restricted to the corpus, but there are other causes of CATG, including Helicobacter infection. This study investigates the presence of IgG4+ plasma cells in gastric mucosal biopsies from patients with a variety of gastric histopathology, including CATG with and without PA.
Design: Archives were searched for patients with the histologic diagnosis of CATG and a history of PA (CATG+PA+, n=46). As controls, archives were searched for 25 patients each with the histologic diagnosis of CATG but no history of PA (CATG+ PA-), patients with normal histology, those with mild chronic inactive gastritis (MCIG), and those with the diagnosis of Helicobacter pylori gastritis (HP).Quantification of Ig G4+ plasma cells were obtained via two methods. 1. Immunohistochemical stain for IgG4 on formalin fixed paraffin embedded tissue. Areas with the highest density of IgG4+ plasma cells were selected, and the average of the 3 most cellular HPFs were counted. 2. To ensure that the number of IgG4+ cells was not simply related to the degree of inflammation (density of plasma cells), dual chromagen immunohistochemical stains for CD138/IgG4 were performed. Areas with the highest density of CD138+ plasma cells were selected, and the number of IgG4+ cells / 200 CD138+ plasma cells was counted. For both methods, the results are interpreted as follows: < 5 considered negative, 5 or more considered positive.
Results: Identical results were obtained by both staining methods. 17/46 (37%) PA patients were positive for increased IgG 4+ plasma cells in. All other groups were negative.