[Measurement of human thyroid peroxidase autoantibodies by enzyme immunoassay using recombinant human TPO]

An EIA for measuring anti-TPO autoantibodies (rhTPO-EIA) was developed using recombinant human TPO expressed in CHO cells and was compared with MC-HA generally used in laboratory routine work. rhTPO-EIA showed a satisfactory reproducibility in the intra-assay test and did not have an accidental error of lots. Almost equal number of healthy females and males were measured for their IgG binding to TPO to define a normal range of anti-TPO autoantibodies. After setting 20 IU/ml as an upper limit of normal range, sera from patient with thyroid disorders were measured for their anti-TPO autoantibodies. Chronic thyroiditis and Graves' disease were highly positive, while adenoma, thyroid cancer, SLE, and RA were low in their positivity. The positive rate of anti-TPO autoantibodies was compatible to those of previous reports in each disorder. Seventy-two sera from patients with chronic thyroiditis or Graves' disease were measured for their autoantibodies by both rhTPO-EIA and MC-HA and the results were compared between both methods. A correlation coefficient was 0.486. Following absorption with thyroglobulin, sera were measured again and as the results, the correlation coefficient increased to 0.723. Therefore, MC-HA was thought to be influenced in the presence of anti-thyroglobulin autoantibodies. Since rhTPO-EIA is excellent in quality and not affected by anti-thyroglobulin antibodies, it is useful and applicable to clinical diagnosis and observation of thyroid disorders.