ELISA is a qualitative method of screening for ANA. When reported as detected or positive, the test will reflex to a fluorescent technique. Negative ELISA results do not necessarily rule out SARD.
ELISA uses antigen-coated microtiter plates for the detection of ANAs. Each microtiter plate well is coated with either a single antigen to detect a specific antibody or multiple antigens to screen for ANAs in general. Serum is incubated in the wells of the plate, and after washing out the plates, any antibodies that bind to antigen will remain on the plate. A secondary anti-human antibody conjugated to an enzyme, such as horseradish peroxidase, is added to the plate. After an incubation period, an enzyme reaction will occur that produces a color change in the solution proportional to the amount of antibody bound to the antigen.
