Subcellular distribution of class II major histocompatibility antigens in enterocytes of the human and rat small intestine

Abstract

Summary Class II antigens encoded within the major histocompatibility complex (MHC) have been examined at the ultrastructura! level in enterocytes from both man and rat. A protocol has been developed for fixation which, in conjunction with a pre-embedding indirect immunoperoxidase technique preserves antigenicity ofthe class II molecules and allows detection of intraeellular antigen. Details of the technique are provided and discussed in relation to the general paucity of information available on ultrastructural localization of class II MHC molecules. Class II MHC antigens have been identified on the basolateral cell membranes of enterocytes in both species and they have also been found in association with intraeellular organdies that have the appearance of multivesicular bodies and secondary lysosomes. These observations link class II molecules with the endocytic pathway in enteroeytes and suggest a possible role in the handling of gut antigens. The findings may have a more general significance in relation to the site of engagement between processed antigen and MHC molecules in specialized antigen-presenting cells.

Differing levels of Mhc class II β chain expression in a range of tissues from vaccinated and non-vaccinated Atlantic salmon (Salmo salarL.)

“…These investigators interpreted these findings to indicate that other cells, possibly epithelial cells, rather than gut leucocytes were mainly responsible for the amount of class II chain transcripts detected in the hindgut. In mammals, epithelial cells in a number of di#erent organs including the intestine carry Mhc class II antigens (Mayrhofer et al, 1983;Daar et al, 1984;Mayer & Shlien, 1987;Bland & Whiting, 1989;Mayrhofer & Spargo, 1989 or can be induced to express Mhc class II under pathological conditions (Marley et al, 1987;Matthews et al, 1988;Masson & Perdue, 1990) or in response to interferon- (Steiniger et al, 1989). Furthermore, Du Pasquier & Flajnik (1990) noted that in Xenopus and especially in tadpoles, cell surface expression of Mhc class II in nonlymphoid cells was concentrated in locations in direct contact with the external environment.…”

Tolerosome‐induced oral tolerance is MHC dependent

“…This requires the assembly of antigen and MHCII for activation of the CD4 + regulatory T cells that are responsible for the oral tolerance. Previous reports have revealed that soluble protein antigens are rapidly pinocytosed from the intestinal lumen and directed to an MHCII‐containing vesicular compartment of the IEC 13,15 . Furthermore, Zimmer et al.…”

“…14 Immunohistochemistry of the small intestines of rodents and humans reveals small MHCII-positive vesicles that are present in abundance in the apical and basolateral part of the IEC. [15][16][17] We have previously shown that these small vesicles, named tolerosomes, are produced by the IEC and constitute the tolerogenic fraction that is found in serum shortly after antigen feeding. 13 Therefore, the induction of oral tolerance by the serum transfer model is referred to as 'tolerosome-induced tolerance'.…”

Professional and non‐professional antigen‐presenting cells in the porcine small intestine

“…Additionally, major histocompatibility complex class II (MHC II) has been found in healthy individuals on stromal cells such as epithelial cells in rodents 14 and humans 15 and on endothelial cells in pigs 16 . The relevance of these stromal cells as APC also needs to be assessed.…”