SIgA is most often measured in feces or saliva. Measuring sIgA in feces can reveal information about gut immunity, inflammation, recent or current infections, and potential acute or chronic stress generally associated with GALT (gut-associated lymphoid tissue). SIgA measured in the saliva primarily provides insight into the body’s stress response, however there is some evidence that activated B cells can migrate from GALT to salivary glands, which could potentially demonstrate systemic inflammation and possibly link GI pathology via salivary sampling.
Elevated levels of sIgA are associated with an upregulated, active immune or inflammatory response, and may be reflective of acute psychological and/or physical stressors. Chronic alcoholics, heavy smokers, and those with oropharyngeal carcinoma have also shown elevations in salivary sIgA.
Decreased levels of sIgA are commonly seen in individuals with low immune system functioning, and are a sign of chronic, ongoing psychological and/or physical stress (HPA axis dysfunction) to the body which has depleted sIgA reserves. SIgA declines with age, and can be seen with some chronic gastrointestinal disorders. Persistent low levels can help to explain why people can’t shift an immune problem like allergies, chronic skin conditions or infections. Lower levels have been associated with increased risk for periodontal disease and caries. 4 Saliva Samples