Anti-gastric parietal cell antibody (GPC)
Antibodies to gastric parietal cells are associated with auitoimmune gastritis and pernicious anaemia. The parietal cells of the stomach secrete intrinsic factor, which is necessary for the absorption of vitamin B12, essential for erythropoiesis. Destruction of parietal cells leads to inability to absorb the vitamin B12 and hence to anaemia.Antibodies against gastric parietal cell antigens are diagnostic of chronic autoimmune gastritis whether resulting in pernicious anaemia or not. Very severe gastric atrophy is necessary before anaemia is detected. Anti-gastric parietal cell antibodies (in the presence or absence of anaemia) are frequently associated with other autoimmune diseases such as autoimmune thyroiditis, insulin dependent diabetes or Addisons disease. Antibodies to intrinsic factor can also be detected in the same diseases.
Anti-GPC antibodies have a high degree of sensitivity (>90%) but are weakly specific; mainly because autoantibodies can predate symptoms by many years. In patients with suspected PA, requests for anti-GPC antibodies should be combined with antibodies to intrinsic factor (please send separate sample to Haematology). Anti-GPC are often detected during autoantibody screen on patient with non-specific symptoms e.g TATT. Around 5% of healthy individuals have low levels of these autoantibodies rising to 10% in older women. They are more common in relatives of patients with autoimmune thyroid disease or gastritis.
The antibodies do appear many years before the onset of pernicious anaemia and therefore patients with high elevated levels should be followed up. Relatives of patients with PA are often weakly Anti-GPC antibody positive (47%) and anti-thyroid antibody positive (67%).
|Indication:||Pernicious anaemia, antral gastritis.|
|Interpretation:||Anti-gastric parietal cell antibodies are found in >90% patients with pernicious anaemia. They are not associated with duodenal ulcer or gastritis which is not autoimmune e.g type B, H. pylori associated gastritis. Anti-gastric parietal cell antibodies are also found in 60% of atrophic gastric and 22% of gastric ulceration cases without detectable anaemia because these conditions occur well before the onset of pernicious anaemia.Anti-gastric antibodies are also found in:
|Sample:||Serum Separator Tube (SST)|
|Assay details:||Indirect immunfluorescence mouse issue (liver, kidney, stomach).|
|Assay range notes:||Positives reported as +, ++ or +++|
|Turnaround time:||5 – 7 days|
|Analysing laboratory:||Immunology The James Cook University Hospital|