Gastric Parietal Cell Antibody

Parietal Cell Antibody:

Why Parietal Cell Antibody Test?

CLINICAL INFORMATION

Parietal cells are also called oxyntic (acid-producing) cells. The function of these cells is to secrete gastric acid (HCl) that helps in the digestion of food, kill harmful bacteria and aids in the absorption of minerals and vitamins such as Vitamin B12. Parietal Cells of the stomach secrete intrinsic factor (IF – Intrinsic Factor: It is a protein that helps the intestine to absorb vitamin B12), required for erythropoiesis (production of RBCs). Auto-antibodies are those immunoglobulins that by formed due to dis-regulation of the immune system (in certain cases with autoimmune diseases), that accidentally recognize self-antigens (of normal and healthy cells) as foreign or non-self (such as bacteria, virus etc), and thus the immune cells are directed against them. Likewise, here the normal and healthy parietal cells of the stomach layer are considered as non-self in some cases and auto-immune response is provoked against it. Thus the Gastric parietal cell antibodies are directed against this self-antigen (i.e parietal cell enzyme – H⁺K⁺ATPase present within the parietal cells). Antibodies against the gastric parietal cells leads to autoimmune gastritis or also called Atrophic Body Gastritis (ABG – inflammation of the stomach lining), hence it results in causing pernicious anaemia (since the destruction of parietal cells results in the inability to absorb vitamin B12 due to destruction of intrinsic factor within parietal cells) triggering in immune-mediated deficiency of vitamin B12 i.e Pernicious anaemia. Pernicious anaemia is a common form of vitamin B12 deficiency anaemia. This is characterized by abnormally large (megaloblastic) RBCs. Pernicious anaemia can be caused either due to vitamin B12 deficiency (lack of dietary intake) and/or due to the intestinal mal-absorption of vitamin-B12 and/or due to decrease or absence of intrinsic factor and/or due to autoimmune disorder. Pernicious anaemia can also be caused due to autoimmune disease - associated with genetic predisposition (a rare congenital form of pernicious anaemia in which neonates are born lacking the ability to produce intrinsic factors effectively). Thus the purpose of this test is to help screen diagnose and confirm the cause for pernicious anaemia (i.e Anti-Parietal Cell Antibodies (APCA) resulting in Auto-Immune Atrophic Gastritis (AAG) leading to Pernicious anaemia. Thus the incidence of Intrinsic Factor Anti-Bodies (IFAB), as well as the occurrence of megaloblastic anaemia along with low serum vitamin-B12, is the screening evidence for diagnosing pernicious anaemia. Thus for patients with suspected pernicious anaemia, both tests for auto-antibodies are required such as parietal cell antibodies (PCA) and intrinsic factor antibodies (IFA) are required for screening for a definitive diagnosis. Symptoms of pernicious anaemia include weakness, headaches, chest pain, weight loss etc. Cause of high Anti-gastric Parietal cell Antibodies is associated with other associated autoimmune diseases also such as autoimmune thyroiditis, Insulin-dependent Diabetes mellitus, Addison’s disease etc. Additional tests include Schillings Test (involves radiolabelled vitamin B12 for testing), ELISA for Antigen or Antibody testing, Histopathology to confirm ABG (Atrophic Body Gastritis), peripheral blood examination (abnormally large RBCs) showing megaloblastic anaemia, vitamin B12 Test to confirm its deficiency (Schillings Test), gastrin test (to confirm elevated levels of serum gastrin from loss of acid secretion, a confirmatory test of PCA - parietal cell antibodies: binding to alpha and beta subunits of the membrane-bound H⁺K⁺ATPase, IFA - Intrinsic Factor Antibodies: binding directly to intrinsic factor and thus preventing B12 from adhesion etc.

General Instructions:

Sample Requirement: Specimen - Blood sample collected from the vein. Test Preparation: None.

NOTE - Sample for specimen collections may vary based on the patient’s condition/cases according to the patient’s presenting complaints/signs or symptoms:

SPECIMEN REQUIREMENT (Special or Rare Cases) - As instructed and guided by Physician / Clinician / Pathologist / as per Laboratory’s requirements, according to procedures and protocols.

This Multi-Specialty Clinical Referral Laboratory RT DIAGNOSTICS provides precise and accurate tests with an extensive range of testing services to the medical centres to help in the diagnosis and identification of pathology in the test specimens for infectious diseases and also to evaluate the function of organ systems of the patient. It prevents further complications and helps to stabilize and restore health to near normalcy at the earliest without delay.