ADHESION MOLECULE EXPRESSION IN-VIVO ON EXTRAOCULAR-MUSCLES (EOM) IN THYROID-ASSOCIATED OPHTHALMOPATHY (TAO)

TAO is an autoimmune condition characterized by mononuclear cell infil tration of the extraocular muscles (EOM) and/or the orbital fat/connec tive tissue with associated deposition of glycosaminoglycans (GAG) in the interstitial spaces. In this study, the presence and distribution of the vascular adhesion molecules intercellular adhesion molecule-1 ( ICAM-1), endothelial-leucocyte adhesion molecule-1 (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1) and the leucocyte integrins CD11a/CD 18, CD11b/CD18, CD11c/CD18 were investigated. Nineteen EOM biopsies we re collected from 17 patients with early (n = 6) and late (n = 13) TAO as well as from 12 non-TAO control patients. Consecutive cryostat sec tions of these biopsies were immunostained with MoAbs to the above-men tioned molecules and haematoxylin and eosin. Primary antibody binding was visualized using an avidin-biotin system. In early untreated TAO s pecimens, the interstitial and perimysial connective tissue surroundin g EOM fibres and numerous mononuclear cells stained strongly for ICAM- 1. In contrast, the vascular endothelial cells (ulex lectin-positive) stained strongly for ELAM-1 (E-selectin), VCAM-1 as well as ICAM-1. In late disease, the same distribution of immunoreactivity for ICAM-1, E LAM-1 and VCAM-1 was observed, but with significantly lower staining. The leucocyte integrins (CD11a, CD11b, CD11c) were again expressed at significantly higher levels in early TAO specimens compared with late TAO specimens and were minimal or absent in the EOM biopsies harvested from control patients. In conclusion, increased expression of adhesio n molecules studied correlated with early active disease and was reduc ed in later stages.