EXPRESSION OF MEMBRANE AND SOLUBLE INTERCELLULAR-ADHESION MOLECULE-1 IN GRAVES-DISEASE

We have investigated the in vitro expression of membrane and soluble i ntercellular adhesion molecule-1 (ICAM-1) by human thyroid cells from 20 patients with Graves' disease and 5 normal subjects. Membrane ICAM- 1 was not detected by flow cytometry analysis in non-cultured thyrocyt es from either normal or Graves' disease tissues. It appeared on thyro id cells after a 24-h culture in monolayers and showed a regular dose- dependent increase. The same results were obtained with soluble ICAM-1 (sICAM-1) in culture media fl om cells cultured in monolayers, vesicl es or follicles. No change was obtained with different concentrations of fetal calf serum added to the media. Coculture of Graves' disease t hyrocytes with autologous peripheral blood lymphocytes (PBL) or intrat hyroidal lymphocytes (ITL) enhanced the expression of both membrane an d sICAM-1 whatever the culture model. When normal thyrocytes were cocu ltured with PBL, sICAM-1 increased but with ITL sICAM-1 remained uncha nged. High concentrations of gamma interferon induced an increase of b oth membrane and sICAM-1 in the three culture models. However the incr eases were greater with vesicles and follicles. Only sICAM-1 levels we re raised with 0.1, 1 and 10 mu M retinoic acid. These results suggest that ICAM-1 appears in culture, possibly due to mechanical effects su ch as adherence to plates and cel-to-cell contacts. Moreover, its expr ession is modulated by several factors such as cytokines or retinoic a cid. further investigations are needed to establish whether ICAM-1 is really involved in the pathogenesis of Graves' disease.