1997 Volume 48 Issue 2 Pages 94-99
The esophageal mucosa forms an active immunological microenvironment different from other mucosal surfaces. In contrast to the intestinal mucosa, its mucous coat is scant, and it has few immuno-inflammatory infiltrates and glandular structures. It is covered by a thick stratified squamous epithelial cell layer, which expresses neither class II MHC antigens nor cell adhesion molecules, but is distributed by class II MHC-positive intraepithelial Langerhans cells as a unique population of antigen-presenting cells. The submucosal vascular unit, however, consists of venule-like blood vessels which constitutively express various cell adhesion molecules, regardless of the presence or absence of inflammation.
In response to certain specific and nonspecific inflammatory stimuli, esophageal squamous cells synthesize and secrete a wide variety of cytokines, which may upregulate the activation of the submucosal vascular endothelial cells and promote infiltration by memory T-cells and neutrophils in inflammatory lesions. In addition, continuous stimuli from the mucosal surface induce cell degeneration and proliferation, and cause progressive genetic changes in the exposed esophageal mucosa.
