To assess correlations between orbital immune cell subsets and the clinical activity in thyroid eye disease (TED).

The orbital samples from 12 healthy controls and 29 TED patients (active group, n=12; inactive group, n=17) were analyzed. Total lymphocytes, CD3+T cells, CD4+T cells, CD8+ T cells, CD3+CD4+CD8+T cells (double-positive (DPT) T-cells), CD3+CD4-CD8-T cells (double negative (DNT) T-cells), B cells, natural killer (NK) cells and NKT cells were counted on flow cytometry. Correlations between the number of orbital immune cells and clinical activity score (CAS) were analyzed.

Age was greater in active than inactive TED patients, and in inactive TED patients than in controls (all P<0.05). TED duration was shorter in active than inactive patients (all P<0.05). FT3 and TSH levels were higher in controls than in active TED patients (P<0.05). There was no significant difference in TRAb level between active and inactive patients. There were no significant differences in smoking status, gender or FT4 level between the 3 groups (all P>0.05). The numbers of orbital total lymphocytes, CD3+ T cells, CD4+ T cells, CD8+ T cells, DNT cells, NK cells, NKT cells and CD4+/CD8+ T cells in active TED patients were significantly higher than in inactive patients and controls (all P<0.05). After adjusting for age and TED duration, the number of CD3+ T cells, CD4+ T cells, CD8+ T cells, NK cells and NKT cells were independent predictors of TED activity (P=0.03, OR=1.19; P=0.04, OR=1.69; P=0.03, OR=1.48; P=0.04, OR=2.08; P=0.03, OR=2.89, respectively).

Numerous immunoinflammatory cells were observed in the orbits of both active and inactive TED patients and in controls, but expression was highest in active TED patients. CD4+ T cell, CD8+ T cell, NK cell, and NKT cell counts were independent factors for the CAS in TED.