Antibodies to gastric parietal cells that react with the cell membrane, cytoplasmic antigens, or gastric intrinsic factor are present in essentially all (>90%) of individuals with pernicious anemia. In 70% of patients, antibodies reactive with the vitamin B12 " �binding site of intrinsic factor are present, and in 50% of patients, additional antibodies are present, which react with a second antigenic site on the 44,000-Da intrinsic factor protein molecule. These autoantibodies lead to a pathologic immune process termed "chronic autoimmune gastritis, " � which may slowly progress for 10 " �20 years and finally terminate in gastric atrophy. The gastric atrophy results in a lack of absorption of vitamin B12 and leads to megaloblastic anemia in patients with anti " �parietal cell antibodies. Pernicious anemia is associated with a variety of other autoimmune diseases including thyrotoxicosis, Hashimoto thyroiditis, insulin-dependent DM, primary Addison disease of the adrenals, primary ovarian failure, primary hypoparathyroidism, vitiligo, Myasthenia gravis, and the Lambert-Eaton syndrome.
Normal range:
IFA: negative; if positive, results are tittered, ELISA: <1:40 titer.
APC titers greater than 1:40 are significant.
Use
Aids in the evaluation of patients suspected of having pernicious anemia
Evaluation of immune-mediated deficiency of vitamin B12 with or without megaloblastic anemia
Interpretation
Increased In
Pernicious anemia
Atrophic gastritis
Diabetes
Gastric ulcer
Thyroid disease
Decreased In
NA
Limitations
High blood levels are also seen in people with inflammation of the lining of the stomach, stomach ulcers, and stomach cancer.
APC antibodies may occur with increased frequency in unaffected family members, a small percentage of healthy individuals, and patients with other autoimmune diseases, such as autoimmune thyroiditis.