MOSAIC DIFFERENTIATION OF HUMAN VILLUS ENTEROCYTES - PATCHY EXPRESSION OF BLOOD GROUP-A ANTIGEN IN A NONSECRETORS

Background:The authors have shown that a mosaicism of brush border antigens may occur spontaneously on enterocytes of small intestine in human adult-type hypolactasia. The present paper gives another example of spontaneously occurring mosaicism as indicated by the patchy expression of blood group antigens on villus enterocytes. Methods: Thirty-five individuals were examined by immunomorphological techniques with antibodies against blood group antigens. Results: In 4 of 16 A blood group individuals, the blood group antigens were expressed only in some villus enterocytes. The individuals with this mosaic pattern were all shown to be nonsecretors. The A antigen in the positive enterocytes of these individuals was only present as the ALeb structure, whereas ALey and ALed were also present in the secretors. The patches of positive enterocytes were randomly distributed along the villus wall. Conclusions: A nonsecretor individuals express the blood group antigens only in some villus enterocytes; this mosaicism does not arise from a heterogeneous population of stem cells within the crypts but rather reflects subtle differences in the pattern of differentiation between monoclonally derived epithelial cells on the villus. © 1993.