Interestingly, more Ag85A antigen was stained in the basolateral compartment of the epithelium (black arrows) than that in apical membrane of intestinal epithelial cells (white arrows) of small intestine (Fig. 1B (f1)). The quantitatively calculated density of positive staining cells in the basolateral compartment showed significantly higher values than those in the apical membrane of intestinal

epithelial MAPK inhibitor cells (p < 0.05) ( Fig. 1B (f2)). To confirm that more intensive expression of Ag85A antigen in the basolateral compartment of the small intestine, immunofluorescent staining of epithelium of the small intestine by anti-Ag85A antibody was conducted. As shown in Fig. 2, more intensive staining of Ag85A antigen was found in Peyer's patches (Fig. 2C (c)), basolateral compartment (Fig. 2C (f)) than that in the apical compartment in the epithelium of the small intestine

(Fig. 2C (i)). The quantitative data showed significant fluoresecent intensity differences between basolateral compartment and apical compartment in the epithelium of the small intestine (p < 0.05) ( Fig. 2f and i). These results suggested that Ag85A antigen was efficiently transported from apical compartment to basolateral compartment. M cells are believed to play a pivotal role in initiation of the immune response at mucosal site, these cells are easily accessible to antigens within the gut lumen and are the route by selleck kinase inhibitor which antigens new enter the PP from the lumen [19]. We next observed expression of Ag85A antigen in M cells after 3 times immunization. Ag85A antigens were substantially expressed in M cells in follicle-associated epithelium (FAE) and in villi adjacent to the lymphoid follicle in orally administrated liposomal-pcDNA3.1+/Ag85A DNA mice (Fig. 3g). In contrast, no Ag85A antigen positive M cells were found in two control groups (data not shown). These results suggested that Ag85A antigens were transcytosed from the lumen and preferentially expressed by M cell pocket. To detect the possibility of Ag85A antigen subsequently transferred to professional antigen presenting cells such as DCs for initiation of Ag85A-specific mucosal immune response, expression of Ag85A

antigen in DCs located in small intestine were detected by immunofluorescent staining. As shown in Fig. 4, Ag85A antigen was undetectable in DCs in small intestinal mucosa of two groups of control mice, but detectable in DCs in the small intestinal mucosa of mice orally administrated by pcDNA3.1+/Ag85A DNA (Fig. 4g). It was also evidenced that Ag85A antigen expressed in the DCs of small intestinal Peyer’s patches, the amount of Ag85A antigen expression was relatively less than that of in M cells (data not shown). In order to examine whether Th1 or Th2 responses are induced in mice orally administrated with liposomal-pcDNA3.1+/Ag85A DNA, IELs were isolated from the small intestine of the mice and stimulated with Con A by day 6 in vitro.