358 Histochemical Study of Allergic Inflammation in Conjunctiva From Ovalbumin Sensitized Rabbits after Ocular or Nasal Challenge

BACKGROUND: We previously demonstrated that subcutaneous sensitization with ovalbumin (OVA) induce generation of specific IgE antibodies and quantitative modifications in immune cells populations from different mucosal sites in rabbit. The aim of the study is characterization of eosinophil infiltration in conjunctival mucosa from OVA sensitized and ocular and nasal challenged rabbits. METHODS: Animals were divided into 4 groups: G1 (n = 9): normal control; G2 (n = 10): subcutaneous sensitized with OVA; G3 (n = 10): subcutaneous sensitized and conjunctival challenged with OVA; G4 (n = 9): subcutaneous sensitized and nasal challenged with OVA. Four hours after challenge animals were sacrificed and obtained samples were processed for histochemistry with cromotrope 2R for eosinophil detection. Cells were counted in 200 high power fields per group. RESULTS: Data were expressed as positive cells per high power field. Conjunctival mucosa: G1: 2.3; G2: 3.4; G3: 12.2; G4: 3.3 (G3 vs G1, G2 y G4 P < 0.001). Specific anti-OVA-IgE levels were evaluated by positive passive cutaneous anaphylaxis test (PCA) at 160 fold dilutions. CONCLUSIONS: We observed an increase in the number of eosinophils-positive cells after local challenge in conjunctiva as compared to normal controls and sensitized and nasal challenged animals. We conclude that systemic sensitization with soluble antigen and conjunctival challenge induces modifications in number of eosinophil populations in conjunctiva but not in nasal challenged rabbits.