SERUM INTRINSIC FACTOR ANTIBODY

Intrinsic Factor (IF), a glycoprotein with a molecular weight of 50 kDA and a member of the eukaryotic cobalamin transport proteins family, is crucial for the absorption of Vitamin B12 in the intestines. Originating from the parietal cells of the stomach, IF plays a key role in facilitating the binding of Vitamin B12 as it transitions from the stomach’s acidic environment. The resulting B12-IF complex undergoes receptor-mediated endocytosis in the ileal mucosa, facilitating its entry into the portal circulation. Pernicious anemia, the most prevalent manifestation of Vitamin B12 deficiency, arises from an autoimmune attack on the gastric mucosa. Initial depletion of parietal cells is succeeded by the formation of autoantibodies against IF, obstructing Vitamin B12 binding sites. In this autoimmune response, two distinct Intrinsic Factor Antibodies (IFAB) types emerge: Type 1, which inhibits the binding site on IF for Vitamin B12, and Type 2, which targets an alternative site, hindering complex attachment in the small intestine. Diagnostic indicators encompass the presence of IFAB, megaloblastic anemia, and reduced serum Vitamin B12. A positive IFAB result eliminates the necessity for supplementary tests, including the Schilling test. Noteworthy is the association of pernicious anemia with various autoimmune diseases such as Hashimoto’s thyroiditis, insulin-dependent diabetes mellitus, Graves’ disease, rheumatoid arthritis, myasthenia gravis, hypoparathyroidism, and Lambert-Eaton syndrome, underscoring the intricate autoimmune landscape linked to this condition, particularly in the context of Hypro Diagnostics.