Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2007) 13 P224

SFEBES2007 Poster Presentations AMEND Young Investigator's Award (21 abstracts)

Clinical impact of thyroglobulin epitope recognition pattern in patients with differentiated thyroid carcinoma and positive thyroglobulin antibodies

Gelsy A Lupoli 2 , Onyebuchi E Okosieme 1 , Carol Evans 1 , Arthur B Parkes 1 , Jean Ruf 1 , Maria R Poggiano 2 , Giovanni Lupoli 2 & John H Lazarus 1


1Centre for Endocrine and Diabetes Sciences, School of Medicine, Cardiff University, Cardiff, United Kingdom; 2Department of Molecular and Clinical Endocrinology and Oncology, University ‘Federico II’, Naples, Italy.


Background: Serum thyroglobulin (Tg) is a useful marker of recurrent or persistent disease in the follow-up of patients with differentiated thyroid carcinoma (DTC); the presence of interfering Tg antibodies (TgAb), even in low concentrations, can lead to a distorted evaluation of this marker. However, TgAb by itself has been shown to be a marker of disease following surgery. TgAb recognition of Tg epitopes differs in pathological and non-pathological states and may thus have prognostic value.

Aim: To determine the epitopes on Tg recognised by TgAb-positive DTC sera and to evaluate whether there is an association between specific TgAb epitope recognition patterns and clinical outcome in patients with DTC.

Methods: All tested sera were TgAb positive. We evaluated TgAb levels and TgAb epitope specificity patterns during the post-surgery follow-up of patients with DTC (n=21) and also in autoimmune thyroid disease (AITD) patients (n=21). Epitope recognition was determined by using 10 Tg monoclonal antibodies (Tg-Mabs) directed against 6 Tg antigenic clusters (I-VI) in competitive enzyme-linked immunosorbent assay (ELISA) reactions with test sera. Tg levels were assessed by immunochemiluminometric assay. We evaluated the disease status of DTC patients, by clinical, biochemical and radiologic examinations.

Results: TgAb levels were comparable in DTC and AITD patients: 1925±299 kUI/l (mean±S.D.) vs 2257±324, respectively (P>0.05). Tg levels were ≤0.5 ng/ml in all DTC patients. TgAb sera from 9 patients with AITD recognized the typical immunodominant clusters I and IV, compared to 7 of DTC patients (P=n.s). Five DTC patients had advanced stage of disease: 2 showed metastatic lymphnodes, 1 a paratracheal mass, 2 local recurrence; none of them had high Tg levels. Four of them showed a distinct Tg epitope pattern involving immunodominant clusters.

Conclusions: We found a similar Tg epitope specificity in both AITD and DTC. Recognition of immunodominant clusters in some patients with DTC maybe associated with a less favourable prognosis.

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