Methodological approach and diagnostic usefulness of a new assay for anti-thyroid peroxidase autoantibodies.
Although thyroid microsomal antibodies (anti-MAb) have been recently proven to be directly to thyroid peroxidase (TPO), current methods for MAb detection still employ unpurified microsomal fractions. The authors have therefore developed and evaluated a specific radioimmunoassay (RIA) for autoantibodies to TPO (anti-TPO Ab) based on competitive inhibition of 125I-TPO to an anti-TPO monoclonal antibody coated on plastic microtiter wells (RIA-1) or tubes (RIA-2). Preliminary experiments showed that both assays were able to specifically detect anti-TPO Ab, while negative results were obtained with normal sera and with sera containing other organ- and non-organ-specific autoantibodies including anti-thyroglobulin antibodies (anti-TgAb). No significant difference in sensitivity, specificity and reproducibility was found between RIA-1 and RIA-2, and the results obtained with the two techniques were therefore pooled together. Anti-TPO Ab were then assayed in 110 normal controls and in 441 patients with different autoimmune (AITD) or non-autoimmune (N-AITD) thyroid diseases and compared to anti-M Ab as assessed by passive hemagglutination (PH). Positive anti-TPO Ab were observed in 4/110 (3.6 p. cent) normal controls, 88/117 (80 p. cent) patients with Graves' disease, 122/123 with Hashimoto's thyroiditis or idiopathic myxedema and 21/201 (10.4 p. cent) with miscellaneous N-AITD. A highly significant positive correlation (r = 0.91, p less than 0.0001) was found between anti-MAb by PH and anti-TPO Ab by RIA ;discrepant results were limited to sera with negative or low (1/100-1/400) anti-M Ab titers.(ABSTRACT TRUNCATED AT 250 WORDS)
Mariotti
S
S
Cattedra di Endocrinologia, Università di Pisa, Italy.
Ruf
J
J
Caturegli
P
P
Rossi
V
V
Boniolo
A
A
Piccolo
P
P
Carayon
P
P
Pinchera
A
A
D001323:Autoantibodies / Q000276:immunology; D001324:Autoantigens / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques; D007453:Iodide Peroxidase / Q000276:immunology*; D008861:Microsomes / Q000276:immunology*; D011863:Radioimmunoassay; D012016:Reference Values; D013954:Thyroglobulin / Q000276:immunology; D013959:Thyroid Diseases / Q000276:immunology*; D013967:Thyroiditis, Autoimmune / Q000276:immunology
D001323:Autoantibodies; D001324:Autoantigens; D013954:Thyroglobulin; D007453:Iodide Peroxidase