What Does a Positive Serum Parietal Cell Antibody Mean?
Anti-gastric parietal cell antibodies (PCA) were first discovered in the serum of patients with pernicious anemia by Taylor et al. The target antigen is located within the membrane of the microvilli of the secretory tubules of parietal cells, which is a lipoprotein component of the cytoplasmic granule and the cytoplasmic membrane. PCA is organ-specific and does not react with other organs outside the stomach, but it is not species-specific, so gastric parietal cells from rats or rabbits can be used as antigens. The Ig classes of PCA are mainly IgG and IgA (with a small amount of IgM), with IgG being the main class in serum and IgA being more common in gastric juice.
The routine detection method is the indirect immunofluorescence (IIF) method using frozen sections of mouse stomach as the antigen substrate. The fluorescent pattern appears as fine granular staining within the parietal cell cytoplasm, often with stronger staining at the apical region. Mouse stomach is a suitable substrate because the stomach of rats may produce false positive reactions. ELISA established with affinity chromatography-purified antigens is also a good method.
The clinical manifestations include loss of appetite, nausea, belching, upper abdominal fullness or dull pain. A few patients may experience upper gastrointestinal bleeding, weight loss, anemia, brittle nails, glossitis, or atrophy of the lingual papillae. Due to the high incidence of this disease and its recurrent and difficult-to-cure nature in clinical practice, as well as its close relationship with the occurrence of gastric cancer, chronic atrophic gastritis has received increasing attention.
