SSB Autoantibody ELISA
The Calbiotech, Inc. (CBI) SSB (La) IgG ELISA Kit is intended for the detection of IgG antibody to SSB in human serum or plasma.
Systemic autoimmune disease is characterized by the presence of circulating auto-antibodies directed to a wide variety of cellular antigens. Systemic lupus erythematosis (SLE), commonly referred to as Lupus is the best known of these diseases. Other possible connective tissue diseases include mixed connective tissue disease (MCTD), Sjogren syndrome, sclerodema, and polymyositis/dermatomyositis. The majority can be diagnosed by clinical presentation and their antibody profiles to the various antigens involved, which include dsDNA, SM, RNP, SSA, SSB Scl-70, Jo1 and Histones. Therefore, immunoassays for autoantibodies are useful for diagnostic and prognostic evaluations of autoimmune disease. The 48 kd phosphoprotein known as SSB (La) is a transcription termination factor for RNA polymerase III. SSB shuttles between nucleus and cytoplasm and exists both free and as a component of the SSA/SSB ribonucleoprotein cytoplasmic particle. Autoantibodies to SSB are detected by ELISA in ~70-90% of primary and ~50% of secondary Sjögren syndrome as well as in ~25% of SLE and ~80% of subacute cutaneous lupus and in the majority of infants with complete heart block. SSB autoantibodies are found only in sera determined to contain SSA autoantibodies by a sensitive method; this probably reflects the association of the SS-A and SS-B antigens in a macromolecular complex.
Diluted patient serum is added to wells coated with purified antigen. IgG specific antibody, if present, binds to the antigen. All unbound materials are washed away and the enzyme conjugate is added to bind to the antibody-antigen complex, if present. Excess enzyme conjugate is washed off and substrate is added. The plate is incubated to allow the hydrolysis of the substrate by the enzyme. The intensity of the color generated is proportional to the amount of IgG specific antibody in the sample.
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