Health Professionals
foodSCAN in Depth
Figure X: YORKTEST IgG food intolerance ELISA-based method
The YORKTEST Laboratories IgG food intolerance test uses an enzyme-linked immunosorbent
assay (ELISA) to detect circulating anti-food antibodies. ELISA methodology is
used extensively in biochemistry and immunology due to its ease of use, reliability
and reproducibility. The method allows for excellent detection levels at low
concentrations.
The ELISA system developed at YORKTEST allows patients to take their own blood sample using the YORKTEST wick, avoiding the complications of collecting a serum sample by a qualified person.
Figure X shows the major steps in the YORKTEST IgG foodSCAN assay. In step 1, the plate is manufactured by YORKTEST’s in-house manufacturing department. Food protein extracts (antigens) are coated onto microtitre plates. Following the binding of the food protein, a stabilising polymer layer is applied which gives stability and shelf-life to the product.
In step 2, the patient’s blood sample is applied across the plate along with standards and controls which are used for calibration and quantification of the result. Should any anti-food antibodies be present in the patient’s sample they will bind to the immobilised food antigen on the plate. The plate is then washed to remove any unbound antibodies and other blood constituents.
Next an enzyme linked second antibody is added as shown in step 3. This antibody will bind to any anti-food IgG antibody present; again the plate is washed to remove unbound material. In the final stage, substrate is added which is converted from colourless to coloured by the enzyme. Colour intensity (optical density) is measured using a visible light spectrophotometer. Therefore, the colour intensity is directly related to the concentration of anti-food IgG antibodies present in the sample.
The laboratory then calculate the result by calibrating the optical density using the reference standards applied to the assay and the result indexed into the user-friendly “no reaction”, “border line” and “avoid” scoring system.
The ELISA system developed at YORKTEST allows patients to take their own blood sample using the YORKTEST wick, avoiding the complications of collecting a serum sample by a qualified person.
Figure X shows the major steps in the YORKTEST IgG foodSCAN assay. In step 1, the plate is manufactured by YORKTEST’s in-house manufacturing department. Food protein extracts (antigens) are coated onto microtitre plates. Following the binding of the food protein, a stabilising polymer layer is applied which gives stability and shelf-life to the product.
In step 2, the patient’s blood sample is applied across the plate along with standards and controls which are used for calibration and quantification of the result. Should any anti-food antibodies be present in the patient’s sample they will bind to the immobilised food antigen on the plate. The plate is then washed to remove any unbound antibodies and other blood constituents.
Next an enzyme linked second antibody is added as shown in step 3. This antibody will bind to any anti-food IgG antibody present; again the plate is washed to remove unbound material. In the final stage, substrate is added which is converted from colourless to coloured by the enzyme. Colour intensity (optical density) is measured using a visible light spectrophotometer. Therefore, the colour intensity is directly related to the concentration of anti-food IgG antibodies present in the sample.
The laboratory then calculate the result by calibrating the optical density using the reference standards applied to the assay and the result indexed into the user-friendly “no reaction”, “border line” and “avoid” scoring system.