A quantitative method for diagnosing an autoimmune disease or an infectious disease comprising performing an automated diagnostic assay, comprising: incubating a capture reagent with a streptavidin-coated medium to form a solid phase complex, wherein the capture reagent is a biotinylated autoantigen or infectious disease antigen; washing the solid phase complex to remove excess capture reagent; incubating the solid phase complex with a serum sample to form an immune complex; washing the immune complex to remove any unbound sample; incubating the immune complex with a conjugate to create an immune-conjugate complex; washing the immune-conjugate complex to remove any unbound conjugate; introducing a substrate capable of generating a quantifiable response; and calibrating the response generated from introducing the substrate.