s-IgA ELISA Kits

Immunoglobulin A (IgA) is a type of immunoglobulin that provides protection from infection. It is mainly distributed in serum and exocrine gland secretions. After IgG, it is the second most abundant immunoglobulin in serum and the most abundant immunoglobulin in exocrine secretions. Human IgA, which has two subclasses, IgA1 and IgA2, occurs mainly as a monomer in serum and as a dimer in secretions¹⁾.

Secretory IgA (s-IgA) is an IgA to which a secretory component (SC) is bound, basically occurring as a dimer but also as tetramer, etc. IgA in secretions occurs principally as s-IgA, which plays an important role in protection from infection on the mucosa of the respiratory and gastrointestinal tracts.

s-IgA is also found in human saliva and produced in plasma cells in the salivary glands. The level of s-IgA in human saliva is reportedly increased by acute stress²⁾ and decreased by chronic stress^{3) 4)}, giving it utility as a stress biomarker.

Human s-IgA ELISA Kit Wako is an ELISA kit for assaying s-IgA in human saliva.

• Kit Performance

  The range of the calibration curve	0.082 - 20 µg/mL
  Assay target	Secretory IgA (s-IgA)
  Sample	Human Saliva
  The sample amount required	5 µL
  Assay time	2.5 hours
  Detection method	Colorimetry
  Within assay variation	CV＜ 6％
  Between assay variation	CV＜ 12％

• Example of Calibration Curve

  

Performance Data

• Spiked recovery test

  Sample	Amount spiked (µg/mL)	Measured value (µg/mL)	Recovery rate (%)
  Saliva１	0	64.8	ー
  	40	108.8	103.8
  	160	220.8	98.2
  	400	404.8	87.1
  Saliva 2	0	46.4	ー
  	40	96.0	111.1
  	160	196.0	95.0
  	400	432.0	96.8
  Saliva 3	0	120.8	ー
  	40	189.6	117.9
  	160	274.4	97.7
  	400	476.0	91.4
  Saliva 4	0	112.0	ー
  	40	157.6	103.7
  	160	244.8	90.0
  	400	441.6	86.3
  Saliva 5	0	105.6	ー
  	40	152.0	104.4
  	160	250.4	94.3
  	400	600.8	118.8

  Cross reactivity with various types of immunoglobulins

  Immunoglobulins	Cross-reactivity (%)
  Serum IgG（Human）	＜0.1
  Serum IgA（Human）	0.3
  Serum IgM（Human）	0.0
  Serum IgE（Human）	0.0

1. de Sousa-Pereira, P. and Woof, J. M.: Antibodies, 8(4), 57(2019).
   IgA: Structure, Function, and Developability
2. Viena, T. D. et al.: Biol. Psychol., 91(2), 307(2012).
   Differential effects of mild chronic stress on cortisol and S-IgA responses to an acute stressor
3. Deinzer, R. et al.: Int. J. Psychophysiol., 37(3), 219(2000).
   Prolonged reduction of salivary immunoglobulin A (sIgA) after a major academic exam
4. Phillips, A. C. et al.: Brain, Behav. Immun., 20(2), 191(2006).
   Stressful life events are associated with low secretion rates of immunoglobulin A in saliva in the middle aged and elderly