Expression of MHC Class II Antigens and Enzymatic Activity in Enterocytes of Germ-Free and Conventional Rats: Dependence on Nutritional Factors During Suckling

Abstract

MHC class II molecules are involved in a variety of immune functions, including presentation of antigens to CD 4+ T cells and regulation of T cell activity.¹ Columnar absorptive cells of the small intestinal villous epithelium have been shown to express class II antigens of the major histocompatibility complex (MHC) in the mouse and the rat.² In the normal adult rat their expression is restricted to fully differentiated columnar epithelial cells on the upper two-thirds of the villus and they are not normally expressed on immature crypt cells.² The expression of class II antigens on epithelial cells can be altered in immune processes; this suggests that they may participate in immune reactions in the gut mucosa.³ The epithelial cells may function as antigen-presenting cells. The exogenous growth factor for lymphocytes, interleukin-2 (IL-2), is produced by T lymphocytes, and its receptor has been found in both lymphoid and non-lymphoid cells.⁴ In the present study we determined the expression of MHC class II antigens in enterocytes of germfree (GF) and conventional (CV) rats, and also in rats after a prolonged intragastric immunization by gliadin.