Context. Thyroglobulin autoantibodies (TgAb) are considered non-pathogenic, because they can be detected in the sera of subjects with no evidence of thyroid disease and do not bind the complement. Their subclass distribution is debated. Radioidine (131I) treatment for Graves’ disease (GD) is one of the events inducing a rise in TgAb levels. Design. Sera with positive TgAb (AIA-Pack, Tosoh Bioscience, Japan) were collected from 25 GD patients (18 females and 7 males), age 41.5 (30.8-56.8) yr, at the time of 131I treatment and three and six months thereafter. To prevent the exacerbation of Graves’ Ophthalmopathy, all patients received oral prednisone. Total TgAb, TgAb light chains and TgAb subclasses weremeasured by ELISA at each time point. Data were analysed by the non-parametric Friedman test and, when the results were significant, values at baseline were compared with those after three and six months in the post-hoc analysis. Results. Total TgAb IgG assessed by ELISA rose significantly (p=0.024): 1:100 (1:100-1:330) before 131I treatment, 1:330 (1:100-1:660) at three months (p=0.10) and 1:330 (1:330-1:1000) at six months (p=0.048). TgAb κ chains did not change (p=0.052), TgAb λ chains increased significantly (p=0.001), being 0 (0-1:100) before 131I treatment, 0 (0-1:330) at three months (p=0.03) and 1:100 (0-1:330) at six months (p=0.002). A significant rise in IgG1 and IgG3 levels was observed after 131I (p=0.008 and 0.006, respectively), while IgG2 and IgG4 levels did not change. The increase in IgG1 levels was persistent: 0 (0-1:100) before 131I treatment, 1:100 (0-1:100) at three months (p=0.028) and 1:100 (0-1:100) at six months (p=0.024). At variance, the increase in TgAb IgG3 was transient: 0 (0-1:100) before 131I treatment, 1:100 (0-1:330) at three months (p=0.028) and 0 (0-1:100) at six months (p=0.72). Conclusions. 131I treatment for GD increases the levels of the complement-activating IgG1 and IgG3 subclasses. In autoimmune thyroid disease the rise in TgAb levels is associated with a switch in their subclass distribution.
Thyroglobulin Autoantibodies Switch to IgG1 and IgG3 Subclasses after 131I Treatment for Graves' Hyperthyroidism: Autoantibodies Subclasses Are Related to the Activity of Autoimmune Thyroid Disease
Francesco Latrofa;Paolo Piaggi;Massimo Tonacchera;Paolo Vitti
2014-01-01
Abstract
Context. Thyroglobulin autoantibodies (TgAb) are considered non-pathogenic, because they can be detected in the sera of subjects with no evidence of thyroid disease and do not bind the complement. Their subclass distribution is debated. Radioidine (131I) treatment for Graves’ disease (GD) is one of the events inducing a rise in TgAb levels. Design. Sera with positive TgAb (AIA-Pack, Tosoh Bioscience, Japan) were collected from 25 GD patients (18 females and 7 males), age 41.5 (30.8-56.8) yr, at the time of 131I treatment and three and six months thereafter. To prevent the exacerbation of Graves’ Ophthalmopathy, all patients received oral prednisone. Total TgAb, TgAb light chains and TgAb subclasses weremeasured by ELISA at each time point. Data were analysed by the non-parametric Friedman test and, when the results were significant, values at baseline were compared with those after three and six months in the post-hoc analysis. Results. Total TgAb IgG assessed by ELISA rose significantly (p=0.024): 1:100 (1:100-1:330) before 131I treatment, 1:330 (1:100-1:660) at three months (p=0.10) and 1:330 (1:330-1:1000) at six months (p=0.048). TgAb κ chains did not change (p=0.052), TgAb λ chains increased significantly (p=0.001), being 0 (0-1:100) before 131I treatment, 0 (0-1:330) at three months (p=0.03) and 1:100 (0-1:330) at six months (p=0.002). A significant rise in IgG1 and IgG3 levels was observed after 131I (p=0.008 and 0.006, respectively), while IgG2 and IgG4 levels did not change. The increase in IgG1 levels was persistent: 0 (0-1:100) before 131I treatment, 1:100 (0-1:100) at three months (p=0.028) and 1:100 (0-1:100) at six months (p=0.024). At variance, the increase in TgAb IgG3 was transient: 0 (0-1:100) before 131I treatment, 1:100 (0-1:330) at three months (p=0.028) and 0 (0-1:100) at six months (p=0.72). Conclusions. 131I treatment for GD increases the levels of the complement-activating IgG1 and IgG3 subclasses. In autoimmune thyroid disease the rise in TgAb levels is associated with a switch in their subclass distribution.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
