Conjunctival macrophages act as antigen-presenting cells in the conjunctiva during the development of experimental allergic conjunctivitis

PURPOSE Antigen (Ag)-presenting cells (APCs) participate in the development of allergic conjunctivitis (AC). However, the conjunctival APCs that take up Ag in AC have not been identified. We sought to clarify the phenotypes of conjunctival APCs that take up, process, and present Ag to T cells during the development of experimental AC. METHODS Splenocytes from naïve ovalbumin (OVA)-specific T cell receptor transgenic (DO11.10) mice were stimulated with either OVA, gold, or OVA-gold to evaluate stimulation-induced proliferation. Naïve DO11.10 mice were subconjunctivally injected with PBS, gold, or OVA-gold. Twenty-four hours later, conjunctivas were harvested for immunohistochemistry and electron microscopy to identify cells that engulfed OVA-gold. RESULTS Stimulation of DO11.10 splenocytes with OVA-gold but not gold alone induced similar levels of proliferation as OVA alone. Subconjunctival injection of OVA-gold, but not gold alone, induced infiltration of eosinophils and CD4-positive T cells into the conjunctiva. The cells that took up OVA-gold into their cytoplasma expressed Cluster of Differentiation (CD) 11b, CD68, major histocompatibility complex (MHC) class II. CONCLUSIONS It appears that conjunctival macrophages are APCs in the development of experimental AC.