Journal of Allergy / 2010 / Article / Fig 1

Research Article

Evaluation of a Novel Rapid Test System for the Detection of Allergic Sensitization to Timothy Grass Pollen against Established Laboratory Methods and Skin Prick Test

Figure 1

Principle of ALFA. A test cassette showing a positive test result is presented in (a) and the principle of the test in (b). The patient’s sample is transferred to the sample application point of the Basis Set. Immediately afterwards, the desired allergen solution is applied. During an incubation time of 20 minutes the liquid is driven through the device by capillary flow. Allergen specific IgE of the sample binds specifically to the corresponding antigens of the allergen solution. The antigens are labeled and are retained at the test line (T) by a capture molecule. At the same time the sIgE bound to the allergen is bound by an antibody coupled to colored particles (conjugate). The intensity of the color reaction at the test line is proportional to the amount of immune complexes consisting of ligand tagged antigens, sIgE, and IgE specific conjugate. The signal intensity ranges from faintly pink (low titer of sIgE) to dark ruby (high titer of sIgE). Access conjugate, which is not bound at the test line, will form a dark ruby control line (C) after 20 minutes of incubation.

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