Mucosal immunology is the study of immune system responses that occur at mucosal membranes of the intestines, the urogenital tract, and the respiratory system.[1] The mucous membranes are in constant contact with microorganisms, food, and inhaled antigens.[2] In healthy states, the mucosal immune system protects the organism against infectious pathogens and maintains a tolerance towards non-harmful commensal microbes and benign environmental substances.[1] Disruption of this balance between tolerance and deprivation of pathogens can lead to pathological conditions such as food allergies, irritable bowel syndrome, susceptibility to infections, and more.[2]
The mucosal immune system consists of a cellular component, humoral immunity, and defense mechanisms that prevent the invasion of microorganisms and harmful foreign substances into the body. These defense mechanisms can be divided into physical barriers (epithelial lining, mucus, cilia function, intestinal peristalsis, etc.) and chemical factors (pH, antimicrobial peptides, etc.).[3]