Assay of Intrinsic Factor Activity on Guinea Pig Intestinal Mucosa Homogenate. ∗

Abstract

Summary and conclusions

The results of the assay of IF activity on fresh or dialyzed and lyophilized guinea pig intestinal mucosa homogenates (GPIMH) with the use of Co⁵⁷B₁₂ are reported. This method has been found suitable for assay of IF activity of native and lyophilized human gastric juices, extracts from human gastric mucosa, rat whole stomach and rat gastric mucosa. The prerequisite for significant enhancement of B₁₂ uptake by the IF-containing materials is an optimal ratio of concentrations of IF to B₁₂ and use of labeled vitamin of high specific activity. Heating of IF sources in boiling water, as well as alkalinization to the pH of 12 and above, reduces B₁₂ uptake to levels obtainable with saline. While native human gastric juices from normal controls or duodenal ulcer patients showed a marked enhancement of B₁₂ uptake by GPIMH, lyophilized gastric juices of 2 pernicious anemia patients showed very low IF activity. A gross correlation was found between results of the GPIMH assays and IF activity of gastric juices when tested by Schilling test on pernicious anemia patients in remission.