Need any help? Call 01353 863279
Cambridge Nutritional Sciences Ltd
Eden Research Park
Henry Crabb Road
Littleport, Cambridgeshire
United Kingdom, CB6 1SE

TEL: 44 (0) 1353 863279
FAX: 44 (0) 1353 863330
Email: orders@camnutri.com
Web: www.camnutri.com

PLEASE NOTE THIS TEST IS BEING DISCONTINUED AT THE END OF APRIL

Technical Literature

The Intrinsic Factor IgG test is a rapid ELISA method for the detection of antibodies to intrinsic factor, a protein involved in the transport of vitamin B12. The components of the test are for in vitro diagnostic use only.

Intrinsic Factor (IF) is an essential glycoprotein involved in the transport of vitamin B12 across the intestinal mucosa. This protein binds to the vitamin forming a complex, which permits B12 absorption into the bloodstream. Vitamin B12 is necessary for the maturation of erythrocytes and a deficiency leads to the development of anaemia.

Failure to produce or utilise IF results in pernicious anaemia. Autoantibodies to IF act by either blocking the formation of the IF-B12 complexes or by binding to other sites on the complexes, preventing absorption.

The determination of serum levels of anti-IF antibodies provides a means to differentiate between autoimmune pernicious anaemia, non-autoimmune pernicious anaemia (e.g. atrophic gastritis and pancreatic exocrine insufficiency) and other forms of vitamin B12 related anaemia.

Principle of the Intrinsic Factor ELISA Test
Diluted serum samples are incubated with recombinant Intrinsic Factor immobilised on microtitre wells. After washing away unbound serum components, rabbit anti-human IgG conjugated to horseradish peroxidase is added to the wells, and this binds to surface-bound antibodies in the second incubation. Unbound conjugate is removed by washing, and a solution containing 3,3’,5,5’-tetramethylbenzidine (TMB) and enzyme substrate is added to trace specific antibody binding. Addition of stop solution terminates the reaction and provides the appropriate pH for colour development. The optical densities of the standards, controls and samples are measured using a microplate reader at 450nm. Optical density is directly proportional to antibody activity in the sample.

References

  • Anaemia - B12 and folate deficiency, Clinical Knowledge Summaries (April 2008)
  • Hoffbrand V, Provan D Macrocytic anaemias BMJ. 1997 Feb 8;314(7078):430-3
  • Chanarin, J. (1979) The Megaloblastic Anaemias, 2nd ed. P 362
  • Blackwell Scientific Publications, Oxford.
  • Conn, D.A. (1986) Detection of type I and type II antibodies to Intrinsic factor. Medical Laboratory Sciences, 43, 148-151.
  • Garrido-Pinson, G.C. Turner, M.D., Crookston, J.H., Samloff, I.M.,
  • Miller, L.L. & Segal, H.L. (1966) Studies of human intrinsic factor auto-antibodies. Journal of Immunology, 97, 897-912.
  • Goldberg, L.S. & Bluestone, R. (1970) Hidden gastric autoantibodies to intrinsic factor in pernicious anemia. Journal of Laboratory and Clinical Medicine, 75, 449-456.
  • Marcoullis, G., Parmentier, Y. & Nicholas, J.P. (1979) Blocking and binding type antibodies against all major vitamin B12-binders in pernicious anaemia serum. British Journal of Haematology, 43, 15-26