Section 866.5110 - Antiparietal antibody immunological test system(a)Identification. An antiparietal antibody immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the specific antibody for gastric parietal cells in serum and other body fluids. Gastric parietal cells are those cells located in the stomach that produce a protein that enables vitamin B12 to be absorbed by the body. The measurements aid in the diagnosis of vitamin B12 deficiency (or pernicious anemia), atrophic gastritis (inflammation of the stomach), and autoimmune connective tissue diseases (diseases resulting when the body produces antibodies against its own tissues).(b)Classification. Class II (performance standards).