Quantification and Characterization of the Phenotype of Conjunctival Dendritic Cells in the Murine Model of Allergic Conjunctivitis

Abstract

Purpose: : Dendritic cells (DCs) have been shown to play a prominent role in various types of allergic inflammation such as asthma and allergic rhinitis. There is a paucity of information in the literature regarding the phenotype of DCs involved in allergic conjunctivitis. The aims of this study are to characterize the phenotypes and density of DCs present in the murine model of allergic conjunctivitis.

Methods: : Female A/J mice were sensitized by an intraperitoneal injection and topical treatment (eye drops) of short ragweed pollen (SRW) with aluminum hydroxide (Alum). The experimental challenge of SRW in phosphate buffered saline (PBS) or PBS only was administered topically. Mice were divided into three groups for analysis: Naïve mice, sensitized/challenged (S/C) mice and sensitized/non–challenged (S/NC) mice. A double immunofluorescence method was used to analyze the phenotypic distribution and density of DC subsets in the mouse conjunctival tissues of the allergic model using a panel of antibodies: CD11c, as a general marker of DCs, coupled with another DC subset marker such as Langerin for Langerhans cells (LCs), CD11b for myeloid DCs (mDCs) and mPDCA–1 for plasmacytoid DCs (pDCs). We also analyzed class II (Ia) expression on DCs using anti–Ia antibody.

Results: : In the naïve conjunctiva, mDCs were consistently detected in the subepithelial layer and substantia propria. In the epithelium and the subepithelial layer very few LCs and virtually no pDCs were observed. Following allergen challenge there was a marked influx of mDCs and pDCs, but no LCs, into the subepithelial layer and throughout the substantia propria. A small number of CD11c+Ia+ DCs were found in the conjunctival tissue in both naive mice and S/C mice but the majority of conjunctival DCs were CD11c+Ia–.

Conclusions: : These results indicate that conjunctival DC subsets may play an important role in the immune–regulatory processes involved in the inflammatory component of allergic conjunctivitis.

Keywords: conjunctivitis • immunohistochemistry • immunomodulation/immunoregulation