T Cell-Related Costimulatory Molecules in the Conjunctiva of Patients with Severe Allergic Conjunctivitis

Backgrounds: We showed previously that costimulatory molecules such as OX40 and 4-1BB participate in the development of murine allergic conjunctivitis (AC). We investigated whether these molecules are expressed in the conjunctiva of patients with severe AC. Methods: Giant papillae were collected from 4 patients with severe AC. As a control, bulbar conjunctivas from 4 normal volunteers were used. Frozen sections of the conjunctivas were stained with anti-CD4, anti-CD8, anti-OX40, anti-4-1BB, or control antibodies (Abs) and then incubated with the biotinylated secondary Ab. Alternatively, staining was performed with a biotinylated anti inducible costimulator (ICOS) Ab. After using an avidin-biotin complex kit, the staining levels were graded from 0 to 3. For immunofluorescence analysis, conjunctival sections were stained with primary Abs that had been fluorescently labeled. Results: The conjunctival stroma of all 4 patients with severe AC were infiltrated with CD4+ and CD8+ cells, whereas only 1 control sample contained stromal CD4+ and CD8+ cells. Conjunctivas from patients but none of the control conjunctivas expressed OX40, 4-1BB, and ICOS. The expression levels of these molecules were significantly higher in patients than the control volunteers. Immunofluorescence analysis demonstrated that the OX40 and 4-1BB, but not the ICOS, molecules were expressed by the infiltrating CD4+ and/or CD8+ cells. Conclusions: Together with the data in murine AC, OX40 and 4-1BB are expressed in the conjunctiva of patients with severe AC but not in the control conjunctivas, which suggests that OX40 and 4-1BB participate, at least in part, in the development of severe AC.