Effect of carbimazole treatment on specific and non-specific immunological parameters in patients with Graves' disease.

Twenty-two patients with newly diagnosed Graves' disease (GD) were treated with carbimazole (CBZ) for 6 months. Thyroid stimulating immunoglobulins (TSI) and T cell subsets were studied prior to treatment and after 3 and 6 months of therapy. TSI were measured on human thyroid epithelial cell monolayers by the cAMP production after the addition of highly purified GD IgG. Before treatment, serum IgG from 20 out of the 22 patients (91%) stimulated cAMP production significantly compared to normal IgG. The mean index of cAMP production (GD IgG relative to normal IgG) was 2.15. After 3 months of CBZ treatment, a non-significant decrease of the mean cAMP production index was observed, whereas it was significantly decreased at the end of the 6 month course of therapy. Before treatment, total T cells (OKT3+), helper/inducer T cells (OKT4+) and suppressor/cytotoxic T cells (OKT8+) were all significantly decreased compared with controls. After 3 or 6 months of CBZ therapy, both total T cells and helper/inducer T cells returned to a normal level, while cytotoxic/suppressor T cells remained at the same low level. Taken together, these data indicate that treatment with CBZ leads to an early increase of helper/inducer T cells followed 3 months later by a decrease of the TSI level with no change in decreased suppressor/cytotoxic T cells. The disappearance of TSI following the increased helper/inducer T cell level suggests that an anti-idiotypic reaction may have occurred, and the persistent decrease of the suppressor/cytotoxic T subset that CBZ therapy does not act upon the underlying autoimmune disease.