Neonatal gastrointestinal mucosal immunity.

The gastrointestinal mucosal immune system is a complex system with multiple interacting cells, which express different markers and elaborate a variety of mediators in response to noxious stimuli and pathogens. At birth this system is quite immature, putting the newborn mammal at risk for a variety of infectious and noninfectious diseases. With age and antigenic stimulation, maturation occurs and intestinal host defense then functions quite effectively to protect the host from ingested noxious substances and microorganisms.