Arnaldo Cantani
The lymphoid tissues of the mucosal surfaces of gastrointestinal (GI), respiratory tracts, etc. on the whole called MALT, in addition to the primary function of preserving sterile the delicate epithelial surfaces in contact with the external environment, should also able to recognize the external antigens and to respond by sensitizing CD4 T cells. If there is a malfunction in normal physiology, the host is at risk of enduring a cell mediated tissue damage.