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Elisa for the measurement of complement C3 activation by autoantibodies directed against thyroid membrane antigens
A B Parkes1, R Harris, S Williams
1Department of Medicine, University of Wales College of Medicine, Heath Park, Cardiff.
This paper describes the use of an ELISA technique to assess the involvement of the complement system in the pathogenesis of autoimmune thyroid disease (AITD). Microtitre plates coated with thyroid membrane antigen were exposed to serum samples obtained from AITD patients, all of whom showed elevated levels of circulating anti-thyroid autoantibodies, and dilute guinea pig serum, as a source of complement, was then added to the microtitre wells. The degree of activation of the classical complement pathway was assessed by measuring the bound complement component C3 using a peroxidase conjugated anti-guinea pig C3 antiserum. C3 fixation and activation was greater in the presence of serum from patients with Hashimoto's disease when compared with that seen in patients with autoimmune hyperthyroidism (Graves' disease). Serum samples obtained from normal healthy volunteers and from patients with thyroid neoplasia were negative in this assay. The method allows the calculation of a putative "biologically active autoantibody" level and analysis of these data confirm our earlier observation that the species of autoantibody found in autoimmune hypothyroidism are potentially more destructive than those found in other forms of AITD.
This paper describes the use of an ELISA technique to assess the involvement of the complement system in the pathogenesis of autoimmune thyroid disease (AITD). Microtitre plates coated with thyroid membrane antigen were exposed to serum samples obtained from AITD patients, all of whom showed elevated levels of circulating anti-thyroid autoantibodies, and dilute guinea pig serum, as a source of complement, was then added to the microtitre wells. The degree of activation of the classical complement pathway was assessed by measuring the bound complement component C3 using a peroxidase conjugated anti-guinea pig C3 antiserum. C3 fixation and activation was greater in the presence of serum from patients with Hashimoto's disease when compared with that seen in patients with autoimmune hyperthyroidism (Graves' disease). Serum samples obtained from normal healthy volunteers and from patients with thyroid neoplasia were negative in this assay. The method allows the calculation of a putative "biologically active autoantibody" level and analysis of these data confirm our earlier observation that the species of autoantibody found in autoimmune hypothyroidism are potentially more destructive than those found in other forms of AITD.