Analysis of Peripheral Blood T-Cell Subsets in Active Thyroid-Associated Ophthalmopathy: Absence of Effect of Octreotide-LAR on T-Cell Subsets in Patients with Thyroid-Associated Ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is thought to be a T-cell–mediated autoimmune disorder. We sought to characterize abnormalities in the peripheral blood T-cell subsets in patients with TAO, and examine whether the long-acting somatostatin analogue, octreotide-LAR, treatment affects these cells. We analyzed peripheral blood T-cell subsets by flow cytometry in 26 euthyroid patients with moderately severe active TAO and 24 controls. Twenty-five of the patients with TAO were enrolled in a randomized trial to receive either 30 mg of octreotide- LAR (n = 11) or placebo (n = 14) every 4 weeks for 16 weeks; all 25 patients subsequently received octreotide- LAR 30 mg every 4 weeks from week 16 to 32. T-cell subsets were analysed at baseline, week 16, and week 32. At baseline, the relative percentage of CD4⁺ helper T-cells (p = 0.0003) and the CD4⁺/CD8⁺ ratio (p = 0.008) were significantly higher in patients with TAO compared to controls. Patients with TAO had higher naïve active T cells (CD45RA⁺, CD45RA⁺CD4⁺) and lower memory T cells (CD45RO⁺, CD45RO⁺CD4⁺) than controls. At weeks 16 and 32, there were no significant differences in any T-cell subsets between the octreotide- LAR–treated and placebo groups. These results support a role of T cell in the pathogenesis of TAO, and show that octreotide-LAR has no effect on T-cell subsets during 32-weeks of treatment.