Molecular and functional morphological studies of M cells

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We have studied that M cells can take up a broad range of macromolecules, microorganisms, and particles and transport them to immunocompetent cells in underlying mucosal lymphoid tissues. It has been shown that the M cells of gut associated lymphoid tissue (GALT) have the role of first information conduit" in the initiation of this local intestinal immunity. "The role of the nasopharyngeal tonsils in antigen uptake for initiation of the mucosal immune response is unknown. This project showed that the M cells ofnasopharyngeal lymphoid tissue (NALT) were ultrastructurally and functionally similar to those in human Peyer's patches and colonic lymphoid follicles. These findings indicate that NALT bears similalities to the GALT, and its antigen uptake capacity may be important for initiation of immunity in the upper aerodigestive tract.At present, the effects of these immunosuppressants on Peyer's patch structure and whether they facilitate or retard M cell uptake and treansport of antigens … More are unknown. The present project examined the effects of these immunosuppressants on Peycr's patches, which play an important role in mucosal immune response through uptake and transport of enteric microorganisms and macromolecules in the gut-associated lymphoid tissues. It was shown that FK and Cs may produce immunosuppressive effects, at least in part, through reduction of the uptake and transport of particles into Peyer's patches, and by reduction of the number of immunoreactive cells in FAE of Peyer's patches.Vimentin has previously been shown to be expressed in rabbit M cells of Peyer's patches and appendixes specifically but not in other gastrointestinal epithelial cells. However, we found that immunoelectron microscopy revealed that the labeled cells in villus epithelium have shorter microvilli than do adjacent absorptive cells and small sparese mitochondria, which are ultrastructural characteristics of cup cells. Vimentin filaments were recognized in the area surrounding the nucleus and extending beneath the plasma membrane of cup cells. In rabbit small intestine, vimentin is useful for detection of cup cells as well as M cells and may facilitate investigation of these little understood cells. Less