Trier J S
Harvard Medical School, Boston, Massachusetts.
Gastroenterol Clin North Am. 1991 Sep;20(3):531-47.
M cells are structurally distinctive, uniquely permeable epithelial cells found only overlying the domes of mucosal lymphoid follicles. Antigenic macromolecules and some viruses, bacteria, and protozoa enter their apical surface by endocytosis or phagocytosis. These substances traverse the M-cell cytoplasm by transcytosis, breaching the epithelial barrier, and then interact with the subepithelial immunocompetent cells to initiate mucosal and systemic immune responses. The M cell serves as a portal of entry for selected pathogens that cause disease locally in the wall of the intestine or, following dissemination, at distant sites. The mechanisms that regulate adherence to and penetration of M cells by macromolecules and microorganisms are not known, but selective binding of secretory IgA to the luminal surface may be important. Whether M cells simply serve a sieving function and always transport substances unchanged across the epithelial barrier or whether they also sort and process antigens they endocytose and present them to adjacent lymphoid cells requires further study.
M细胞在结构上具有独特性，是仅存在于黏膜淋巴滤泡穹隆上方的具有独特通透性的上皮细胞。抗原性大分子以及一些病毒、细菌和原生动物通过胞吞作用或吞噬作用进入其顶端表面。这些物质通过转胞吞作用穿过M细胞的细胞质，突破上皮屏障，然后与上皮下的免疫活性细胞相互作用，引发黏膜和全身免疫反应。M细胞是特定病原体进入的门户，这些病原体可在肠道壁局部引发疾病，或在扩散后在远处部位引发疾病。调节大分子和微生物对M细胞的黏附和穿透的机制尚不清楚，但分泌型IgA与管腔表面的选择性结合可能很重要。M细胞是仅仅起到筛分功能，总是将物质原样穿过上皮屏障进行转运，还是它们也会对其内吞的抗原进行分选和加工，并将其呈递给相邻的淋巴细胞，这需要进一步研究。
