sPSGL-1 Inhibits Eosinophil Recruitment in an Ocular Allergic Inflammatory Model

Atopic diseases which include bronchial asthma, allergic rhinitis, atopic dermatitis, and ocular allergic disorders are among the most frequent conditions experienced by patients. Allergic conjunctivitis, an atopic ocular disease, is one of the most common problems encountered in general ophthalmic practice and the only ocular inflammatory disease that represents a pure type-I hypersensitivity response. Other ocular diseases, some of which are associated with blinding corneal complications, have more complex immunological and inflammatory components. However, a unifying component of all forms of ocular allergy is the presence of eosinophils, a major inflammatory cell in the IgE-mediated late-phase reaction. Current medical therapy for ocular allergic disorders is primarily symptomatic. To assess the efficacy of new treatment modalities and study the pathophysiology of ocular allergy, we have used a murine model that closely resembles human allergic conjunctivitis. SWR/J mice develop clinical (conjunctival congestion and erythema) and histological (eosinophil infiltration) signs of allergic conjunctivitis after exposure to short ragweed pollen. Moreover, the SWR/J mouse model represents a pure type-I hypersensitivity response to a natural allergen. As eosinophils are a hallmark of the late-phase response, the mechanisms that mediate their recruitment are integral to an understanding of allergic inflammation.