Effects of technetium-99 methylenediphosphonate on cytokine-induced activation of retro-ocular fibroblasts from patients with Graves' ophthalmopathy.

Objective: To explore the effects of technetium-99 methylenediphosphonate (99Tc-MDP) on cell proliferation, hyaluronic acid (HA) synthesis and the expressions of human leucocyte antigen-DR (HLA-DR), intercellular adhesion molecule-1 (ICAM-1) on cultured retro-ocular fibroblasts (RFs) from patients with Graves' ophthalmopathy.

Methods: After two to seven passages, cultured RFs were incubated for 72 h with interferon-γ (100 U/ml), interleukin-1 (100 U/ml) or tumour necrosis factor-α (100 U/ml) in the presence of 99Tc-MDP. Flow cytometry was used to investigate the expression of HLA-DR and ICAM-1. RF proliferation was assessed by 3H-thymidine incorporation assay. HA synthesis was measured by radioimmunoassay.

Results: At base conditions, the percentage of positive cells of HLA-DR and ICAM-1 on RFs was 6.70±3.06% and 5.29±3.02%, respectively, and the synthesis of HA was 337.8±42.7 ng/ml. Compared with basal values, 72-h incubation with cytokine significantly enhanced the expression of HLA-DR and ICAM-1, and HA synthesis. 99Tc-MDP (1 ng/ml) had little effect on cytokine-induced HLA-DR and ICAM-1 expression, and HA synthesis. When the concentration ranged from 10 to 100 ng/ml, 99Tc-MDP inhibited cytokine-induced RF activation in a dose-dependent manner. 99Tc-MDP also inhibited the proliferation of RFs in a dose-dependent manner. It was also found that 99Tc-MDP had the same effect on cytokine-induced RFs and skin fibroblasts from patients with normal individual conditions.

Conclusions: 99Tc-MDP could inhibit cytokine-induced activation of RFs derived from patients with Graves' ophthalmopathy.