Immune corneal rings. I. Evaluation of reactions to equine albumin.

Ring reactions of the cornea have been given a new nomenclature based upon their mechanism of formation. The term immune corneal ring includes all types and distinguishes ring reactions from the general term, "anaphylactic" keratitis. The systemic immune ring, arising slowly from serum antibody ami cells at the limbus, is distinguished from the local immune ring, which rapidly develops at the "target site" of injection. The former type develops from a single corneal injection, whereas the latter is dependent upon at least one reinjection of antigen and appears to begin independently of systemic immunity. A local tissue antibody of as yet undetermined origin is postulated to stimulate the formation of local immune rings. The origin of the cellular component of local rings is still undecided. Systemic immune rings which are another manifestation of the Wessely phenomenon and which normally develop about 2 weeks after sensitization tuill usually develop within 6 or 7 days in animals previously sensitized systemically; the accelerated reaction can occur as early as 1 day after challenge. Reactions that develop in 1 or 2 days after intracorneal challenge can occur in the absence of demonstrable corneal vascularization. A delayed hypersensitivity component is postulated to account for the tissue damage observed in some of the corneas. The importance of the breed of rabbit used in this type of study is emphasized.