Characterization of macrophages in the conjunctiva during the development of experimental immune–mediated blepharoconjunctivitis

Abstract

Abstract: : Purpose: We have been dissecting the developing mechanism of experimental immune–mediated blepharoconjunctivitis (EC) as a model for severe types of human allergic conjunctivitis such as chronic atopic keratoconjunctivitis. In EC, macrophages as well as eosinophils were identified in the conjunctiva. Here we aimed to characterize macrophages in the conjunctiva during the development of EC. Methods: EC was induced by either active or passive immunization of OVA followed by OVA challenge. Eyes including conjunctivas were harvested either before or after challenge at different time–points. Eyes were examined immunohistochemically. To deplete macrophages in the conjunctiva, 48, 24 hr or just prior to challenge. clodronate liposomes were injected subconjunctivally into rats received of OVA–specific T cells. Eyes were harvested 24 hrs after challenge for immunohistochemistry. Results: MHC class II positive and ED1 or ED2 positive macrophages existed constitutively in the conjunctiva. Confocal analysis demonstrated that macrophages express MHC class II molecules. Induction of EC increased infiltrating MHC class II positive ED1 cells in the conjunctiva. Inhibition of macrophage infiltration by clodronate liposomes was noted. Conclusions: These data suggest that macrophages in the conjunctiva could be antigen–presenting cells for the development of EC and might be involved in the chronic tissue damage in the conjunctiva.

Keywords: conjunctivitis • immunohistochemistry • pathology: experimental