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Secretory IgA (sIgA) – The Power of Immune Exclusion for Seasonal Allergies

Secretory IgA (sIgA) – The Power of Immune Exclusion for Seasonal Allergies
Secretory IgA (sIgA) - The Power of Immune Exclusion for Seasonal Allergies
By Med Support News March 2, 2025

Secretory IgA (sIgA) - The Power of Immune Exclusion for Seasonal Allergies

Secretory IgA (sIgA) – The Power of Immune Exclusion for Seasonal Allergies

If you could send your patients out into the world with a shield along every mucosal surface to help prevent infection and allergic responses, would you? The potent shield naturally secreted onto every mucosal surface is the specialized antibody known as secretory IgA (sIgA), and you can test sIgA levels in all patients. Secretory IgA works via immune exclusion, which is characterized by blocking pathogens, allergens, and other antigens from entering the body.

Secretory IgA physically binds to and blocks antigens – including pollen, influenza, dust, coronaviruses, pet dander, and others – from causing an infection or allergic response. Secretory IgA is the best ally to have around when seasonal allergies bloom!

Secretory IgA (sIgA) - The Power of Immune Exclusion for Seasonal Allergies

The Mucosal Immune System – The First Line of Defense During Allergy Season

The moist tissues that line the nasal passages, sinuses, mouth, and throat are known as mucosal surfaces. Since these surfaces are exposed to the outside world, they have a robust mucosal immune system to protect them. With every breath, airways are exposed to innumerable and invisible toxins, allergens, and pathogens. If mucosal immunity is not optimal, allergens and respiratory viruses can quickly invade the body, causing inflammation, infection, and dysfunction.1

One of the first lines of defense against allergens (and pathogens!) is an extraordinary and specialized antibody known as Secretory IgA (sIgA), which is naturally produced by the mucosal immune system. Nutrient deficiencies, chronic stress, high cortisol levels, chronic infections, and other factors can significantly diminish the production of protective sIgA.2-5

The Mucosal Immune System - The First Line of Defense During Allergy SeasonWhat is Secretory IgA (sIgA)?

Secretory Immunoglobulin A, also known as Secretory IgA or sIgA, is a specialized antibody that functions outside the body on mucosal surfaces. IgA was first discovered in 1953 and is the most abundant immunoglobulin produced along the mucosal surfaces.6 Studies show approximately 74% of all mucosal antibodies are IgA antibodies.1

Immunoglobulin A (IgA), or monomeric IgA, is one antibody isotype produced by the immune system. Other antibody isotypes include IgG, IgD, IgE, and IgM. To produce sIgA, two IgA molecules are linked together along with a secretory component. Secretory IgA is also referred to as multimeric or dimeric IgA.1,7 More IgA antibodies are produced daily than the total amount of all other antibody isotypes combined.1 This picture depicts the structure of the different antibody isotypes:The Mucosal Immune System - The First Line of Defense During Allergy SeasonSecretory IgA is considered a protective and anti-inflammatory antibody, while other antibodies primarily have an inflammatory effect. For example, when an IgG antibody interacts with a pathogen, it has the ability to kill it, which sounds beneficial, but this process can cause a high level of inflammation that damages cells and tissues.8 IgA antibodies can prevent infections and allergic reactions via several mechanisms that minimize systemic inflammation and damage.

Because of its unique immunosuppressive and immunomodulatory capabilities, IgA helps to maintain homeostasis at the mucosal barrier. Maintaining a balance in inflammatory and anti-inflammatory activity is a challenge since the mucosal surfaces are permanently exposed to an enormous variety of both harmful and harmless organisms, compounds, and molecules.9 More research has been performed on the protective activities of sIgA in the GI tract than in the airways. However, similar mechanisms are likely to occur in the respiratory mucosal tissues to maintain health during the allergy season.9

The Mucosal Immune System - The First Line of Defense During Allergy SeasonSecretory IgA – Blocking Allergens & Pathogens to Maintain Seasonal Health for Life

Secretory IgA begins to protect health in infancy since it is the predominant immunoglobulin present in breastmilk. In infants, the sIgA in breast milk protects against acute infections, reduces the risk of allergies, and supports lifelong health. Research shows a lack of sIgA in early life due to being formula-fed rather than breastfed may increase the risk of developing inflammatory bowel disease (IBD), obesity, allergies, and autoimmune disorders, including asthma.6

The total surface area of the respiratory and digestive tracts is approximately 200 times larger than that of the skin. Approximately 60–70% of white blood cells reside in the mucosal tissues for protection since the mucosal surfaces are incessantly exposed to microorganisms, allergens, and toxins from the outside world.5 Secretory IgA is secreted in and binds to the mucus layer that covers and protects the mucosal surfaces from allergens and pathogens, including viruses.9

Secretory IgA (sIgA) - Reduce & Prevent Seasonal Allergies

How Does Secretory IgA (sIgA) Prevent Viral Infections?

Secretory Immunoglobulin A (sIgA) is a unique and protective antibody that operates on the moist surfaces of the mouth, throat, and sinuses, safeguarding them from the innumerable substances they encounter from the surrounding environment. Secretory IgA serves as a preventive barrier against viral infections (and allergens), minimizing inflammation and damage to the body.9

Secretory IgA and the mucosal immune system are truly indispensable during the cold and flu season, shielding areas of the body that are most exposed to external elements.8,9 In the GI tract, research shows sIgA protects the mucosal tissues from infectious pathogens by:

  • Neutralizing pathogens, including viruses
  • Developing the composition of the beneficial commensal microbiota
  • Preventing harmful inflammatory responses to pathogens, foods, allergens, and other substances that interact with the mucosal surfaces9

Doctors and scientists suspect sIgA protects the respiratory tract from allergens and pathogens via similar mechanisms.9 When present in mucosal secretions, sIgA molecules bind to infectious pathogens, including viruses, thus preventing their adhesion and entrance into the body. The bound sIgA molecules then facilitate their elimination.2,10

Preventing the adhesion and absorption of pathogenic organisms while also facilitating their removal is a phenomenon known as “immune exclusion.” Two additional methods by which sIgA molecules reduce the likelihood of viral infections include direct interference with surface receptor binding and a reduction in the activation and expression of pathogenic virulence factors.2

Secretory IgA (sIgA) - The Power of Immune Exclusion for Seasonal Allergies

How Does sIgA Reduce & Prevent Seasonal Allergies?

Secretory IgA plays an important role when seasonal allergies are prevalent. Monomeric IgA and sIgA antibodies modulate allergic immune responses via several mechanisms.10

Mucosal sIgA prevents the absorption and promotes the elimination of allergens via immune exclusion. Immune exclusion reduces and prevents inflammatory and allergic responses against the allergens. Furthermore, mucosal sIgA forms aggregates with allergens in secretions that can impact inflammatory signaling.10

Monomeric IgA induces anti-inflammatory responses. Monomeric IgA also directly competes with IgE for binding with allergens, thereby diminishing IgE-mediated allergic reactions.10

Are you and your patients adequately protected by sIgA antibodies?

Secretory IgA (sIgA) - Reduce & Prevent Seasonal Allergies

The Secretory IgA (sIgA) Test

It is wise to assess total intestinal and salivary sIgA levels at least once or twice annually to observe any aberrations in immune resilience. Being proactive about testing and optimizing sIgA production will keep you and your patients prepared for seasonal allergies, the cold & flu season, and other immune challenges year-round.

Secretory IgA (sIgA) - Reduce & Prevent Seasonal AllergiesNaturally Boost Secretory IgA (sIgA) Levels for a Pleasant Allergy Season

Research indicates that a combination of lifestyle modifications and supplements can help maintain optimal sIgA production. Consider:

  1. Nutritional support, such as Zinc, Selenium, and Vitamins C, E, A, and D311-18
  2. Herbal assistance from Adaptogens (Ashwagandha), Astragalus, and Elderberry19-22
  3. Probiotics, including Lactobacillus, Bifidobacterium, and Saccharomyces boulardii22-35
  4. Stress management techniques, like meditation, therapy dogs, and music3,36-44
  5. Regular moderate exercise and resistance training45-48

Secretory IgA (sIgA) - Reduce & Prevent Seasonal Allergies

Keep yourself and your patients healthy year-round by testing for and optimizing the production of sIgA.

DiagnosTechs offers several test panels that assess sIgA levels.

Total Salivary Secretory IgA (sIgA) can be ordered as part of an:

Total Intestinal Secretory IgA (sIgA) can be ordered as part of a:

Total Intestinal sIgA and Total Salivary sIgA can also be ordered as single tests.

Secretory IgA (sIgA) - Reduce & Prevent Seasonal AllergiesTo place a test order, click here. As a reminder, DiagnosTechs will drop ship test kits directly to your patients. You may select this option at the top of the order form.

 

Please visit our Provider Tools page for more information about choosing the right test and mucosal immunity.

Secretory IgA (sIgA) - Reduce & Prevent Seasonal AllergiesReferences:

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