Thyroglobulin autoantibodies in iodized subjects: relationship between epitope specificities and longitudinal antibody activity.
BACKGROUND
We previously reported a high thyroglobulin autoantibodies (TgAb) prevalence in healthy Sri Lankans after iodine supplementation. In the present study 58 TgAb-positive schoolgirls were followed up after 5 years of continued iodination. The objectives were: (1) to observe the longitudinal profile of TgAb epitope specificities and (2) to examine the relationship between these specificities and the course of thyroid autoimmunity in this population.


METHODS
Paired subjects' sera (at onset and at 5-year follow-up) were tested for TgAb, thyroid peroxidase antibody (TPOAb), and TgAb epitope-specificity. Epitope reactivity was determined by employing a panel of 10 murine monoclonal antibodies (Tg-mAbs) directed against 6 Tg antigenic clusters (I-VI) in competitive enzyme-linked immunosorbent assay (ELISA) reactions with test sera.


RESULTS
The overall pattern of epitope recognition in individual subject's sera remained preserved over the time period. Nine subjects showed restricted specificities while majority of the subjects were broadly heterogeneous. At follow-up, median TgAb concentration in the restricted group was higher than in the unrestricted (1650 versus 110 kIU/L; p < 0.005). Epitope specificity was a stronger determinant of TgAb persistence than the height of the initial TgAb response or the TPOAb status of subjects.


CONCLUSIONS
Tg epitope reactivity pattern in iodised populations may identify subjects at greater risk of developing autoimmune thyroid disease (AITD).
Okosieme
O E
OE
Department of Medicine, University of Wales College of Medicine, Cardiff, United Kingdom.
Premawardhana
L D K E
LD
Jayasinghe
A
A
Kaluarachi
W N
WN
Parkes
A B
AB
Smyth
P P A
PP
Lejeune
P J
PJ
Ruf
J
J
Lazarus
J H
JH
D000469:Alkaline Phosphatase / Q000032:analysis / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000032:analysis; D000918:Antibody Specificity; D001323:Autoantibodies / Q000032:analysis*; D001667:Binding, Competitive; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D013188:Sri Lanka; D013954:Thyroglobulin / Q000276:immunology*; D013960:Thyroid Function Tests
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D000939:Epitopes; D013954:Thyroglobulin; D000469:Alkaline Phosphatase