[Immunohistochemical study of interstitial keratitis in an animal model]

We performed an immunohistochemical study on the development of interstitial keratitis in a rabbit model sensitized by ovalbumin (OA).

A mixture of OA (5 micrograms/ml) and Freund's complete adjuvant was initially injected subcutaneously (0.4 ml) into the rabbits' back and footpad (0.2 ml). After a week, the rabbits were sensitized by an injection of the same solution into the back (0.5 ml) again. After 4 weeks the rabbits underwent the same treatment as a booster shot. Then a week later OA solution (0.05 ml) was injected into the corneal stroma. We observed the cornea on days 1-3, 7, and 10 after the corneal treatment. Corneas on days 3 and 10 were examined by immunohistological methods using hematoxylin-eosin stain, methylgreen pyronin stain, and by immunohistochemical methods with anti-CD 4, anti-CD 8, and anti-OA antibodies. The localization of specific antibodies was identified by fluorescent-antigen method. Electron-microscopic observation was also done.

Rabbits developed corneal opacity and edema on day 1, corneas had on immune ring with a peak intensity on day 3, and vascularization on day 7 after corneal treatment. Microscopic examination revealed infiltration of neutrophils in to the area of the immune ring on day 3 and many plasma cells at the limbus and stroma on day 10. CD 4 positive cells were found at the limbus and stroma on days 3 and 10. CD 8 positive cells were found at the limbus and stroma only on day 10. OA positive findings were observed at the immune ring and its inner area. In the fluorescent-antigen method, specific antibodies were found in plasma cells at the limbus on days 3 and 10.

In our experimental model of interstitial keratitis with immune ring and vascularization, the Arthus reaction was dominant. Infiltration of antigen specific plasma cells in the stroma with vascularization caused a modification of pathologic reaction in keratitis.