Test Kit Example - Not necessarily representative of this test.
Reagent volumes/configurations are suitable for manual use, automated Mago® systems, and Dynex DSX™ and DS2™ systems.
For the detection and semi-quantitation of antibodies against the Sm/RNP antigen in serum as an aid in the diagnosis of autoimmune disease.
Summary and Explanation
Systemic rheumatic disease is characterized by the presence of circulating autoantibodies that are widely reactive with both nuclear and cytoplasmic antigens. The RNP and Sm antigens consist of portions of the U1 RNA and nine associated polypeptides. Antibodies to Sm/RNP are detected in up to 40% of patients with systemic lupus erythematosus (SLE) either alone or in conjunction with Sm antibodies.
The RNP antigen is very closely associated with the Sm antigen and is designated the Sm/RNP complex. In contrast to anti-Sm, anti-RNP is found in patients with a variety of rheumatic diseases including scleroderma, rheumatoid arthritis, discoid lupus, polymyositis and Sjogren’s Syndrome. High titers of anti-RNP, in the absence of anti-Sm, are correlated with mixed connective tissue disease (MCTD).
Until recently, many laboratories used Immunodiffusion (ID), Counterimmunoelectro-phoresis, and hemagglutination to detect RNP antibodies. However, these methods are time consuming and cumbersome to perform and are insensitive relative to newer methods. Enzyme immunoassay (EIA) has advantages over the ID method in sensitivity, specificity, ease of automation, and testing turnaround time.
The Diamedix Is-anti-Sm/RNP Test Kit is an EIA procedure intended for the semi-quantitation of antibodies to RNP antigen. The results are reported in ELISA units (EU) per ml determined by comparison to a Calibrator.
Principle of the Procedure
Purified Sm/RNP antigen from calf and/or rabbit thymus is bound to microwells. Diluted patient sera, Calibrator, and controls are placed in the microwells and incubated. Anti-Sm/RNP antibodies, if present, will bind to the antigen in the microwells. After washing the microwells to remove unbound antibodies, a second incubation with anti-human IgG conjugated to alkaline phosphatase is carried out. The conjugate will bind to human anti-Sm/RNP antibodies, if present, forming an immunocomplex. The microwells are then washed again to remove unbound components and the enzyme substrate, para-nitrophenylphosphate is added. The enzyme, if bound, will catalyze the hydrolysis of the substrate to para-nitrophenol and result in formation of a yellow color. The reaction is then stopped and the color read with a photometer at 405 nm (reference at 600-630 nm). The intensity of the color developed is proportional to the concentration of anti-Sm/RNP IgG present in the sample.
Please refer to the complete Package Insert for more information.