From the Guidelines
Anti-parietal cell antibodies serve as diagnostic markers to assist in the diagnosis of autoimmune gastritis, as recommended in the 2021 clinical practice update by the American Gastroenterological Association 1. The primary purpose of these antibodies is to help identify patients with autoimmune gastritis, a condition where the immune system attacks the parietal cells in the stomach lining. Key points to consider when evaluating the purpose of anti-parietal cell antibodies include:
- They target the H+/K+ ATPase proton pump in parietal cells, disrupting intrinsic factor and hydrochloric acid production.
- Their presence indicates an immune system attack on parietal cells, potentially leading to vitamin B12 deficiency due to decreased intrinsic factor production.
- Testing for these antibodies is typically ordered for patients with symptoms of vitamin B12 deficiency or unexplained gastric inflammation/atrophy.
- The presence of anti-parietal cell antibodies is highly sensitive (80-90%) for autoimmune gastritis, although not entirely specific, as they can be found in other autoimmune conditions like Hashimoto's thyroiditis or type 1 diabetes, as discussed in the context of autoimmune gastritis diagnosis 1. When diagnosed with pernicious anemia due to these antibodies, patients usually require lifelong vitamin B12 supplementation, typically through injections, as oral absorption is compromised.
From the Research
Purpose of Anti-Parietal Cell Antibodies
The purpose of anti-parietal cell antibodies (APCA) is to serve as a diagnostic tool for autoimmune atrophic gastritis (AAG) and pernicious anemia (PA) 2.
Target and Detection of APCA
- The target for APCA is the H+/K+ ATP-ase, with the alpha subunit being the major antigen 2.
- APCA can be detected by means of immunofluorescence, enzyme-linked immunosorbent assay (ELISA), and radioimmunoprecipitation assay (RIA) 2.
- RIA is the most accurate method of antibody assessment, characterized by highest sensitivity 2.
Prevalence of APCA
- APCA can be found in 85-90% of patients with PA 2.
- They are also found in the circulation of individuals with other diseases, such as type 1 diabetes, autoimmune thyroid diseases, vitiligo, and celiac disease 2.
- APCA are present in 7.8-19.5% of the general healthy adult population 2.
Association with Other Conditions
- APCA are found in up to 20.7% of patients with Helicobacter pylori infection 2.
- The presence of APCA is associated with an increased risk of gastric carcinoma 3.
- APCA-positive patients are more likely to have associated autoimmune diseases and be diagnosed by a case-finding strategy 4.