Salivary IgA and Other Secretory Products
Jeffrey W. Terryberry, B.S.

The sublingual, submandibular and parotid glands are salivary exocrine glands which are involved in initial digestive processes as well as in oral host defense against pathogens. The salivary glands are composed of secretory acinar cells, myoepithelial cells and ducts which convey secretions. Secretion is primarily controlled by the autonomic nervous system.1 Acinar cells produce electrolytes which generate an electrochemical gradient involved in secretion. Saliva is involved in soft tissue repair, inhibition of bacterial aggregation and plaque formation, and in digestion. Salivary amylase cleaves 1-4 and 1-6 saccharide branch points on ingested carbohydrates. Mucins are involved in food lubrication; whereas, lipase degrades long-chain triglycerides; the proteases (kallikrein, gelatinase and collagenase) degrade proteins. Salivary lactoperoxidase is involved in blood flow regulation; whereas, salivary lysozyme possesses antimicrobial activity. Other constituents include growth hormones, lactoferrin, albumin and immunoglobulins.1-3 Citrate-stimulated salivary gland flow rates are about 0.5 mL/min/gland; whereas, basal rates are 0.1 mL/min/gland.4 Nicotine reduces salivary lactoferrin and lysozyme secretion; whereas, the anti-gingivitis agent, delmopinol has no effect on salivary lysozyme.5,6

Salivary IgA is an important first-line defense against pathogens and can be used in the diagnosis of infections. Normal salivary IgA secretion rates (~150 mg/min) decrease with stress and aging.7 Specific salivary IgA antibodies can be detected against Candida albicans, Streptococcus mutans, EBV, adenovirus and HIV-1.8-10 Salivary IgG antibodies are also useful in the detection of Helicobacter pylori, CMV, parvovirus B19 and importantly, HIV infections.11-16 Recombinant HIV-1 gp120 vaccine induces both specific salivary IgA and IgG.17 Tonsillectomy reduces total salivary IgG and IgM, but overall antimicrobial defense is unimpaired.18 Salivary autoantibodies to gliadin in celiac disease, thyrotropin receptor in Graves disease, and salivary ductal epithelium cytokeratin in Sjögren syndrome are also described.19-21 The oral pathogens Streptococcus sanguis, S. oralis and S. mitis are able to secrete proteases that specifically degrade salivary IgA.22 Salivary IgA production is reduced by anti-epileptic drugs, anxiety and Papillon-Lefevre syndrome.23-25 Salivary IgA is increased in diabetics; whereas, lysozyme concentrations are decreased.26-28 Other sialochemical analyses are also useful. Periodontal diseases can alter the salivary secretions of cystatin, amylase, a2-macroglobulin, C-reactive protein, cathepsin G, elastase, lysozyme, lactoferrin and lactoperoxidase.29-31 Salivary IgA was used to create a gingival immunologic defense index in the evaluation of risk for periodontal disease.32 Patients with recurrent parotitis demonstrate elevated concentrations of salivary albumin, IgA, lactoferrin, lysozyme and kallikrein; whereas, HIV-infected individuals have raised salivary cortisol.33,34 Both amylase and low molecular weight mucins interact with the oral pathogens Actinobacillus actinomycetemcomitans and Streptococcus gordonii.35,36


Relevant Tests Offered by GBMC
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REFERENCES

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