SECRETORY IgA1 (sIgA1) ELISA KIT
INTENDED USE
The Secretory IgA1 (sIgA1) ELSIA Kit Assay is intended for the quantitative determination of secretory IgA1 (sIgA1) in saliva and stool. For in vitro diagnostic use only.
INTRODUCTION
Secretory IgA (sIgA) consists of two IgA monomers joined by the J-chain and an additional secretory component. It is secreted in plasma cells located in the lamina propia of mucosal membranes. Synthesis of sIgA is independent from the synthesis of serum IgA. This means that lack of serum IgA does not necessarily correlate with a lack of sIgA1. Secretory IgA is the major immunoglobulin in saliva, tears, colostrum, nasal mucous, mother’s milk, tracheobronchial and gastrointestinal secretes. It plays a major role in preventing adherence of microorganisms to mucosal sites, in activation of the alternative complement pathway and in activating inflammatory reactions. Newborns are provided with sIgA by mother’s milk and are passively immunized against gastrointestinal infections.
The human IgA exists in two isotypic forms: IgA1 and IgA2, which differ both in their primary amino acid sequences and carbohydrate structures. The distribution of the two IgA subclasses in secretions is dependent on the mucosal site: IgA1-secreting cells predominate in the respiratory tract, in the upper gastrointestinal tract and in mammary glands (60–93%), whereas IgA2-secreting cells predominate in the lower gastrointestinal and in the female reproductive tracts.
PRINCIPLE OF THE TEST
Secretory IgA1 (sIgA1) ELSIA Kit
The Secretory IgA1 (sIgA1) ELSIA Kit Assay is intended for the quantitative determination of secretory IgA1 (sIgA1) in saliva and stool. In a first incubation step, the sIgA1 in the samples is bound to polyclonal rabbit antibodies (in excess), which are immobilized to the surface of the microtiter wells. To remove all unbound substances, a washing step is carried out. In a second incubation step, a Peroxidase-labeled mouse antisIgA1 conjugate is added. After another washing step, to remove all unbound substances, the solid phase is incubated with the substrate, Tetramethylbenzidine (TMB). An acidic stop solution is then added to stop the reaction. The color converts from blue to yellow. The intensity of the yellow color is directly proportional to the concentration of secretory IgA1 in the sample. A dose response curve of the absorbance unit (optical density, OD) vs. concentration is generated, using results obtained from the calibrators. Secretory IgA1, present in the patient samples, is determined
directly from this curve.
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