Secretory Immunoglobulin A ELISA Kit (sIgA)


Human secretory IgA ELISA kit is an accurate in vitro quantitative method for detecting secretory immunoglobulin A (sIgA) in human saliva, serum, urine and milk samples. This assay has a minimum sensitivity detection limit of 0.6 µg/ml.


Secretory immunoglobulin A (sIgA) is an antibody which has vital roles in mucosal immunity, it is also a subclass of immunoglobulin A (IgA). The main immunoglobulin in mucus secretions from the salivary glands, tear glands, mammary glands, gastrointestinal tract, genitourinary tract and the respiratory system. The intestinal cells can produce approx. 2-3g every day, this tends to reach a peak during childhood and begins to decline after the age of sixty.

Many people think of mucus being in the nose and sinuses, however, actually there is a greater amount present in the gut. The sticky lining of mucus is our primary line defence against any gastrointestinal pathogens such as bacteria, viruses, fungi, parasites and food proteins. The sIgA antibodies are able to prevent micro-organisms, carcinogens and food proteins from binding to the surface of absorptive cells. Essentially, they are able to attach themselves to invading pathogens, trap them in mucus and prevent them from going anyway. They effectively neutralise any damaging toxins given off and ensure that these are excreted from the body appropriately.

Secretory IgA is produced by B-lymphocytes that are located adjacent to the mucosal cells and then it is transported through the cell interiors until finally it is released as secretions from the cells. It is not synthesised by mucosal epithelial cells in these structures or even derived from blood. It exhibits a diurnal rhythm, displaying highest levels in the morning which then decrease to the lowest in the evening.

There is a difference in the levels that are present in saliva depending on the secreting glands, with the highest levels found in minor saliva glands. The concentrations in saliva vary in response to psychological and physical stress through a complex interaction with the autonomic nervous system. The levels in saliva can also be affected by the flow rates, where usually the concentrations tend to decrease as flow rates increases.


All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

  • Microwell Plate: Coated with murine antibody to secretory IgA (monoclonal).
  • Calibrator Set (1-6): Concentrations 0, 2, 20, 40, 100, 400 µg/ml.
  • Control Serum.
  • Enzyme Conjugate: Containing murine monoclonal to  IgA alpha chain conjugated to HRP.
  • EIA Buffer.
  • Sample Diluent EIA Buffer.
  • TMB Substrate Solution.
  • Washing Solution (Concentrated).
  • Stop Solution.
  • Plate Sealing Tape.
  • Instructions.
  • QC Data Sheet.


The minimum sensitivity detection limit of secretory Immunoglobulin A (sIgA) using this sIgA ELISA kit was approximately 0.6 µg/ml. The dynamic assay range for this kit is 2.0 – 400.0 µg/ml.


– Expected Values: Serum (1.6 – 5.0 µg/ml), Saliva (57 – 260 µg/ml), Urine (0.5 – 2.7 µg/ml), Breast Milk (lower limit 800 µg/ml).
– Analytical Specificity/Cross Reactivity (% wt/wt): IgG (< 0.1%), IgM (< 0.1%), IgE (< 0.1%).
– Analytical Sensitivity: 0.6 µg/ml
– Linearity: 90 – 110%
– Recovery: 90 – 110%


  1. An update on minor salivary gland secretions. Eur J Oral Sci. (2010) 118 (5): 435-42. Review. Eliasson L. and Carlén A.
  2. SIgA binding to mucosal surfaces is mediated by mucin-mucin interactions. PLoS One. (2015) 10 (3): e0119677. Gibbins H.L., et al.
  3. A simple and rapid competitive enzyme-linked immunosorbent assay (cELISA) for high-throughput measurement of secretory immunoglobulin A (sIgA) in saliva. Talanta. (2010) 82 (1): 432-6. Wang D., et al.
  4. Tear Fluid SIgA as a Noninvasive Biomarker of Mucosal Immunity and Common Cold Risk. Med Sci Sports Exerc. (2016) 48 (3): 569-77. Hanstock H.G., et al.
  5. Secretory A immunoglobulin, total proteins and salivary flow in Recurrent Aphthous Ulceration. Braz J Otorhinolaryngol. (2007) 73 (3): 323-8. Martinez Kde O., et al.


  • Full Name: Secretory Immunoglobulin A ELISA Kit (sIgA)
  • Reactivity: Human
  • Sample Type: Saliva, Serum, Urine, Milk
  • Sensitivity: 0.6 µg/ml


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Your secretory IgA ELISA gave good results and I was also really impressed with how quickly we received it.

L. Johnston
PhD Student / University of Glasgow

It is refreshing to know that you have a technical team that is very knowledgeable. I have already recommended your company to other researchers in our department.

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Lecturer / University College London (UCL)

I am a first time user and found that your instruction manual was very easy to follow. The insulin ELISA assay performed well and I was happy with the results that were generated.

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Senior Technician / Addenbrooke’s Hospital

I carried out a pilot study comparing the performance of many ELISA assay's from different suppliers and found your kits to be one of the better performers. We observed good linearity and tight replicates.

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Lead Scientists / AstraZeneca

You are my first point of contact when I am looking to purchase ELISA. You have such an easy and simple system, yet it is very effective.

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Purchasing / University of Oxford