Distribution of ‘Intrinsic Factor’ Activity

Abstract

After preincubation with hog intrinsic factor concentrate (HIFC), marked enhancement of Co⁶⁰-labeled vitamin B₁₂ uptake at 0°C by rat and human liver slices and by segments of rat small intestine was observable. No such marked enhancement by HIFC was observable in rat kidney, heart or spleen slices. After preincubation with serum from normal human beings or patients with pernicious anemia, slight enhancement of Co⁶⁰-B₁₂ uptake by rat liver slices was noted; marked enhancement was noted after preincubation with a 15-fold concentrate of normal human serum. The hypothesis is presented that there may exist a ‘circulating intrinsic factor’ involved in the selective deposition of vitamin B₁₂ in the human liver.