The Salimetrics SIgA kit will pick up all forms of IgA, but not the free secretory piece alone. The concentration of IgA in saliva is minimal compared to the very high concentrations of SIgA. The Salimetrics SIgA kit measures both secretory IgA and monomeric IgA; it uses a polyclonal antibody and it is not specific for secretory IgA. It measures monomeric IgA (as found in serum) which accounts for approximately 15% of total IgA in saliva and diffuses into saliva from serum. The other 85% of IgA in saliva is true secretory IgA.
2018-01-18