​Signosis’ Autoimmune ELISA Kits detect autoimmune antibodies in human serum using a standard ELISA format. A specific antigen is pre-coated onto microtiter wells to capture the target antibodies. During the assay, the sample is added, and autoimmune antibodies, if present, bind to the immobilized antigen. An HRP-conjugated anti-human IgG antibody is then added, forming a complex. After washing away unbound proteins, TMB substrate is added, which reacts with HRP to form a blue color. Then, Stop solution is added to terminate the reaction and change the blue color to yellow. The intensity of the yellow color, measured at an absorbance of 450 nm, is directly proportional to the concentration of autoimmune antibodies in the sample.