Anti-Jo-1 antibody is a myositis specific autoantibody most commonly found in patients of Polymyositis (PM) and Dermatomyositis (DM). PM and DM are idiopathic inflammatory myopathies, characterized by proximal muscle weakness, elevated muscle enzyme activities and electromyographic and histological feature. This antibody is directed against the histidyl-tRNA synthetase which catalyses the binding of the histidine to its cognate tRNA during protein synthesis. Anti-Jo-1 antibody is predominantly found in 20-30% of PM patients and 60-70% of PM with interstitial pulmonary fibrosis. The antibody is also found in DM, although less frequently than in PM. , It is rare in children with PM or DM and in other connective tissue diseases. Moreover, the serum levels of anti-Jo-1 antibody strongly correlate with disease activity representing a good marker for disease monitoring.
Autoimmune ELISA kits measure autoimmune antibodies in the serum. It is based on the principle of a solid phase enzyme-linked immunosorbent assay. The assay utilizes a specific antigen for immobilization on the microtiter wells and anti-human IgG antibody conjugated to horseradish peroxidase (HRP) for detection. The test sample is allowed to react simultaneously with the two components, resulting in autoimmune antibodies being sandwiched between the solid phase antigen and the enzyme-linked antibodies. After incubation, the wells are washed to remove unbound antibodies. Then an HRP substrate is added to develop a blue color. The color development is stopped with the addition of Stop Solution changing the color to yellow. The concentration of autoimmune antibodies is directly proportional to the color intensity of the test sample. Absorbance is measured spectrophotometrically at 450 nm.