Autoimmune gastritis/ pernicious anaemia

Diagnosis for Autoimmune gastritis (AIG) depends upon high circulating levels of antibodies against the parietal cell antigens and those directed against intrinsic factor (IF). Intrinsic factor aids in the absorption of vitamin B12 in the ileum. Two types of antibodies have been recognized:

• IFA type 1 that reacts with vitamin B12 binding site
• Typ2 that reacts with the receptor cells of the ileum

IFAs are very specific for AIG. They are positive for 40 to 80 percent of the patients with pernicious anemia.

The next big thing is to look for antibodies against parietal cell antigens (PCA). They are both of IgG and IgA types. Seen in almost all patients of chronic atrophic , PCAs are also high diagnostic accuracy for pernicious anemia (PA) accounting for 80 to 90 percent of the cases. However, during the course of the disease, the prevalence decreases due to destruction of the parietal cells. One should keep in mind that these antibodies are also seen in patients with endocrinopathies and healthy blood donors.

Antibodies against PCA can be detected by immunofluorescence assays or by ELISA. IFA can be detected by intrinsic factor biochips or ELISA. We also offer blot techniques to differentiate the diagnosis from other diseases such as celiac or Crohn’s disease.