ASSAY FOR INTRINSIC-FACTOR BASED ON BLOCKING OF THE R BINDER OF GASTRIC-JUICE BY COBINAMIDE

  • 1 January 1979
    • journal article
    • research article
    • Vol. 53  (4) , 788-793
Abstract
An in vitro assay for measurement of [human] gastric juice intrinsic factor (IF) was developed based on the ability of the cobinamide (Cbi) [(CN, OH) Cbi] to bind to the gastric juice R-type binders of cobalamin (Cbl) and not to the IF binder. Subsequently added radioactive Cbl, CN-[57 Co] Cbl, bound only to the IF binders and allowed for direct measurement of this Cbl binding protein. This Cbi blocking assay functioned as well as the more conventional methods of IF measurement, G-100 column chromatography and IF blocking antibody assay. The present assay has the advantage of eliminating the need for elaborate forms of protein separation and does not rely on a source of antibody. [The most common cause of Cbi deficiency is pernicious anemia (PA) characterized by deficient secretion of IF. Although measurement of the output of IF can be used to make or exclude the diagnosis of PA, this approach has not enjoyed wide clinical application.].