Regional variation in expression of major histocompatibility class II antigens in enterocytes of postnatal and adult mice

The constitutive expression and ontogeny of major histocompatibility class II antigens in enterocytes of small intestine of adult and postnatal C3H/He mice were investigated. In adults, the immunoreaction revealed that the expression of class II antigens was greatest in ileum and decreased proximally towards the duodenum. The villus epithelium of the duodenum showed a granular staining pattern in the apices of some cells. In jejunum, granular immunostaining within apical and basal regions of the cells lining the villus was observed. Ileal enterocytes demonstrated an intense cytoplasmic and baso-lateral immunoreaction for the antigens.

Ontogenic studies revealed that the first appearance of class II antigens in enterocytes coincides with age of weaning, suggesting that immunologic stimulation by ingested antigens after weaning may influence expression of these antigens. There is an age-dependent regional variation in expression of class II antigens in enterocytes, and the expression increases with age. The crypt epithelium of three regions of the small intestine showed expression similar to that of corresponding regional villus enterocytes. The variation in expression of class II antigens in enterocytes of postnatal mice is attributed to the developmental status of the tissue. (Abstract shortened by UMI.).