The gastrointestinal tract is also a prominent part of the immune
system.
The low pH (ranging from 1 to 4) of the stomach is fatal for many
microorganisms that enter it. Similarly, phlegm (containing IgA antibodies) neutralizes
many of these microorganisms.
Other factors in the GI tract help with immune function as well,
including enzymes in the saliva and bile.
Enzymes such as Cyp3A4, along with the antiporter activities,
are besides helping in the intestine's role of detoxification of antigens and
xenobiotics, such as drugs, involved in first pass metabolism.
Health-enhancing intestinal bacteria gastrointestinal
minister to to prevent the overgrowth of potentially disadvantageous bacteria
in the gut. Microorganisms are also kept at bay by the agency of an large immune
system comprising the gut-associated lymphoid tissue (GALT).
