Chapter 1 - Development and Physiology of Mucosal Defense: An Introduction

Abstract

This chapter reviews how different components of the mucosal barrier develop. The mucosal barrier, like the skin, defines the boundary between the host and its environment. The mucosae of the gut and respiratory tract absorb substances that are essential for life. To maintain immunosurveillance, antigens are transported across the intestine in physiologic amounts, but pathologic transport may occur when the mucosal barrier is breached. Mechanisms that allow passage of antigen through the intestinal epithelium in controlled amounts are an essential prelude to B-cell activation. The T-cell responses, on the other hand, are initiated by presentation of short peptides bound to major histocompatibility complexes (MHCs). Patients with cystic fibrosis, in which pancreatic activity is severely affected, have an increased incidence of cow's milk allergy, because of increased antigen uptake. The gastric acidity and pancreatic activity may be less in the newborn and this can have consequences on the development of the mucosal barrier.