A rat model of ocular contact hypersensitivity was employed to investigate migration of Langerhans' cells (LCs) into the central corneal epithelium. One group of rats was cutaneously sensitized with 5 μl of 50% dinitrochlorobenzene (DNCB) in olive oil. Subsequently, both sensitized animals and nonsensitized controls were topically challenged with 5 μl of 10% DNCB in olive oil applied to the external surface of the eye. Corneas were excised at various time intervals ranging from 0 to 21 days following challenge, and whole-mounted epithelial sheets were histochemically stained. Quantitative cell counting of a 12.5-mm2 area of central corneal epithelium revealed significantly greater numbers of LCs in epithelium of sensitized animals as compared to controls with a maximal difference on day 14 (p = 0.013). The abnormal presence of LCs in central cornea may play a role in the perpetuation of corneal inflammation resulting from contact hypersensitivity reactions of the eye.
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