AIM:To examine the specimens of iris,ciliary body and retina from patients with sympathetic ophthalmia for the expression of costimulatory molecule CD28,CTLA-4 and its ligands B7-1(CD80)and B7-2(CD86).METHODS:The paraffin-embedded sections of sympathetic ophthalmia were obtained based on the specimens of 4 patients with sympathetic ophthalmia and 2 healthy persons,and analyzed by immunohistochemical method with polyclonal antibody probes for B7-1,B7-2,CD28 and CTLA-4 molecules.RESULTS:The specimens of normal iris and ciliary body showed B7-2 expression.B7-1 was found in the normal choroids.B7,CD28 and CTLA-4 molecules did not express in the normal retina.However,in the sympathetic ophthalmia,the iris and ciliary body showed B7-1,B7-2,CD28 and CTLA-4 molecules expression.Approximately 100% of retina pigment epithelium cells expressed B7-1 and B7-2 molecules,but not CD28 or CTLA-4 molecules.In the specimens of retina,there was low expression of B7-1,B7-2,CD28 and CTLA-4 molecules.CONCLUSION:The results of this study indicate that the interaction between B7 and CD28,CTLA-4 may contribute to the sustained immune activation in the uvea of the patients with sympathetic ophthalmia.