Current laboratory methods for the detection of autoantibodies in the serum include immunofluorescence microscopy (IFA) and immunochemical assays (ELISA). Reading IFA patterns can be time consuming, subjective and prone to misinterpretation. A further limitation of this approach is that it does not define the specific antigen and thus is unable to provide information for the design of more specific treatment strategies. ELISA assays are targeted at specific antigens but they can only quantify one autoantibody at a time.
AMiDot™ slides contain an autoimmune antigen microdot array, an internal calibrator curve and negative and positive controls in each well. A mixture of recombinant and purified native antigens are used for the microdot arrays to ensure reliable and reproducible results. Available slides can measure 8 or 4 patients per slide and be run either manually or on automated IFA slide processors such as the DAS AP16 IF Plus alongside existing IFA slides. The patient sample is diluted 1:81 and then 65µL of diluted patient serum is incubated on each microdot array for 30 minutes. The slides are washed and the autoantibodies that bind to their specific antigens are detected with an anti-human IgG/IgA conjugate containing a fluorescent tag. After processing the slides are imaged using the dedicated fluorescence reader and analysed to produce a patient report listing the concentration and positive or negative status of the autoantibodies.
Validation of the operator handling and reagent quality are assessed using the internal calibration and positive and negative controls. All autoantibodies are calibrated to available international reference preparations and CDC controls.