Mucosal immune responses reviewed.

2004 JUL 7 - (NewsRx.com & NewsRx.net) -- Scientists review mucosal immune responses in a recent issue of Best Practice & Research in Clinical Gastroenterology.

"The host gastrointestinal tract is exposed to countless numbers of foreign antigens and has embedded a unique and complex network of immunological and non-immunological mechanisms, often termed the gastrointestinal 'mucosal barrier', to protect the host from potentially harmful pathogens while at the same time 'tolerating' other resident microbes to allow absorption and utilization of nutrients," investigators in the United States report.

"Of the many important roles of this barrier, it is the distinct responsibility of the mucosal immune system to sample and discriminate between harmful and beneficial antigens and to prevent entry of food-borne pathogens through the gastrointestinal (GI) tract," said David W. K. Acheson and Stefano Luccioli at the Food and Drug Administration. "This system comprises an immunological network termed the gut-associated lymphoid tissue (GALT) that consists of unique arrangements of B cells, T cells and phagocytes which sample luminal antigens through specialized epithelia termed the follicle associated epithelia (FAE) and orchestrate coordinated molecular responses between immune cells and other components of the mucosal barrier."

"Certain pathogens have developed ways to bypass and/or withstand defense by the mucosal immune system to establish disease in the host," stated the researchers. "Some 'opportunistic' pathogens (such as Clostridium difficile) take advantage of host or other factors (diet, stress, antibiotic use), which may alter or weaken the response of the immune system. Other pathogens have developed mechanisms for invading gastrointestinal epithelium and evading phagocytosis/destruction by immune system defenses. Once cellular invasion occurs, host responses are activated to limit ...