Serum. Blood serum.
Anti-DNA antibodies. Simple blood tests can be performed to test for anti-dna antibodies. Usually the screen is started with a basic ANA test which can then be followed with more specific antibody testing to determine if a specific disease can be identified. Of course, symptoms must also correlate since we do not simply provide diagnosis based on lab findings.
Radioactivity. The farr assay is a radioimmunologic assay. It uses radiolabeled antigens to detect specific antibodies in serum. The antigens are allowed to react with the serum and then precipitated using a special reagent such as protein a sepharose beads. The bound radiolabeled immunoprecipitiate is commonly analzyed by gel electrophoresis.
Anti-DNA antibody. People with lupus develop abnormal substances in their blood called antibodies. These antibodies attack various organs of the body and cause the signs and symptoms of the disease. Anti-dna antibody is one such substance. The exact reason why people develop these antibodies is not known but there is often a genetic component (family history).