Persorption of Luminal Antigenic Molecule and Its Specific Antibody via Apoptotic Epithelial Cells of Intestinal Villi and Peyer's Patches into Peripheral Blood in Rats

Abstract

ABSTRACT. The possibility of persorption of bovine serum albumin (BSA) molecules from mucous epithelial cells and its mechanism were investigated in rats orally pre-immunized by BSA for 14 consecutive days. In the small and large intestines, both the BSA antigen (BSAAg) and its specific antibody (SpAb) were absorbed by the epithelial cells at the late apoptotic stage (ApoEp), and were subsequently transcytosed by membranes of the small vesicles. The basal cytoplasms containing highly-concentrated BSA-Ag and SpAb were occasionally fragmented into small cytoplasmic droplets that were secreted into the lamina propria. In Peyer's patches, both BSA-Ag and SpAb were more actively absorbed and transcytosed toward the dome area by the ApoEp of the dome apex than by the M cells. BSA-Ag and SpAb were finally persorbed into the portal blood and lymph, but were never secreted into the bile. They were also engulfed by macrophage-like cells in the villous lamina propria, mesenteric lymph node and spleen, and by hepatocytes in the liver. These findings suggest that sensitized soluble luminal antigens are taken up by ApoEp in the small intestine and are finally persorbed into the peripheral blood. The uptake of luminal antigen might be mediated by its luminal SpAb.

Persorption Mechanisms of Luminal Antigenic Particulates via Apoptotic Epithelial Cells of Intestinal Villi into Systemic Blood Circulation in Orally Immunized Rats

“…The food antigen and its immune complex are absorbed and transported into peripheral blood in adult humans [8,18]. Our previous study suggests that the absorption and transcytosis of the luminal BSA-antigen are mediated by its SpAb in small intestines of orally BSA-immunized rats [47]. In the present study, BSA-SE absorption in orally BSA-immunized animals was significantly more frequent than in animals with no oral immunization or no BSA-coated SE administration.…”

“…Moreover, the epithelial cells with more active absorption of the BSA-antigenic molecules were also accompanied by stronger nuclear DNA fragmentation in the orally immunized rats [47]. Our present study suggests that engulfment of antigenic particulates occurred in the apoptotic epithelial cells at the villous apices that contacted the BSA-SEs containing chyme.…”

“…According to our previous study, the BSA-antigen molecule and its SpAb are absorbed by apoptotic microvillous columnar epithelial cells at the apices of intestinal villi and FAEs of Peyer's patches in orally BSA-immunized rats. From these epithelial cells of the apices, the BSA-antigen molecule and its SpAb are t r a n s p o r t e d t o s u b e p i t h e l i a l t i s s u e t h r o u g h a n intracytoplasmic route that is composed of small vesicles [47]. In the present study, the SEs that were attached to the apical membrane of epithelial cells were engulfed by epithelial cells and transported through the epithelial cytoplasm to the subepithelial tissue.…”

“…The engulfment of bacteria by M cells in the rabbit appendix requires the bacteria to be able to access the FAE [26]. Moreover, both the BSA-antigen and its SpAb are absorbed by apoptotic apical epithelial cells in the apical FAE rather than by M cells in the basal FAE of Peyer's patches in orally BSA-immunized rats [47]. In the present study, no SEs reached the FAEs in any experimental groups because of prevention of diffusion of SEs by both the adjacent follicle-associated intestinal villi and mucous.…”

“…In situ nick-end labeling method: The bromodeoxyuridin triphosphate (BrdUTP) method was applied to detect the final features of the apoptotic villous columnar epithelial cells according to the method described by Yuji et al [47]. Briefly, four sections were prepared (Sections 1, 2, 3, and 4).…”