Conjunctival basophil hypersensitivity lesions in guinea pigs. Analysis of upper tarsal epithelium

The upper tarsal conjunctival epithelium was analyzed for inflammatory cell profile and accompanying morphological changes in a guinea pig system with histopathology resembling two human ocular diseases: vernal conjunctivitis and contact lens-associated giant papillary conjunctivitis (GPC). Female Hartley strain guinea pigs were immunized intradermally on day 0 with 200 micrograms keyhole limpet hemocyanin (KLH) and challenged on day 6 with varying doses of KLH by injection beneath the conjunctival epithelium of one lid and phosphate-buffered saline in the contralateral lid. Tissues containing the reaction site were examined by light microscopy. The 50 micrograms dose of KLH elicited the maximal accumulation of basophils and eosinophils. These values were significantly higher than in the PBS-injected control. Injection of KLH, PBS, or insertion of a sterile needle into unsensitized animals, and uninjected tissue served as additional controls. Neutrophils were significantly higher in the epithelium of the traumatized tissue (repeated needle insertions) than in the uninjected control. Basophils and mast cells were rarely found in the epithelium of unsensitized animals. Epithelial thickening, quantified by a Zeiss Videoplan2 Image Analysis system (Zeiss, West Germany), was greatest in the traumatized tissue, followed by the KLH-challenged tissue of sensitized animals. These values were significantly greater than that of the PBS-injected lid or of naive animals, uninjected or KLH-injected. These results indicate that epithelial changes can be induced by both antigen and trauma. Such epithelial changes may have a role in both vernal conjunctivitis and giant papillary conjunctivitis.