The specific aims of the experiments proposed here are: 1. to identify the subsets of lymphocytes present in corneal immune reactions; 2. to determine the functions of the specific lymphocyte subpopulations present in corneal immune reactions; 3. to develop a reproducible and quantitative alternative model to the experimental cornea allograft procedure; and 4. to compare the effectiveness of topical cyclosporine with topical steroids in preventing or suppressing corneal immune reactions. Inbred rats of one strain will be given intracorneal injections of allogeneic keratocytes from a second inbred strain. The fate of the injected keratocytes and the host response to the allogeneic keratocytes will be determined. Enumeration and identification of specific lymphocyte subsets of host origin in the keratocyte-injected corneas will be accomplished by histological and immunohistochemical methods. The immunoperoxidase staining technique, coupled with antibody specific for lymphocyte subset markers, will permit accurate analysis of the recipient's response to the allogeneic keratocytes. Specific functions of intracorneal lymphocytes will be determined by a modified plaque assay technique developed to permit study of B and T lymphocytes. Immunologically competent lymphocytes synthesize and secrete biologically potent mediators that exert a regulatory action on effector cells. The modified plaque assay technique will be used to identify intracorneal lymphocytes that secrete specific mediators. A new experimental analog of the cornea transplant will be developed and the lymphocyte subset(s) responsible for this reaction will be identified by cell fractionation techniques. The time course of this model and the optimum nunber of lymphocytes necessary to establish the model will be determined. Cyclosporine, the promising new immunosuppressive agent, will be tested as a topical immunosuppressive in the alternative corneal allograft model, in an effort to establish the potential usefulness of this drug in clinical ophthalmology. Corneal immune reactions, such as the allograft reaction, are serious clinical problems. By developing and investigating a variety of experimental systems and by determining the cellular and humoral components of corneal immune reactions, it will be possible to better understand and medically treat such reactions in humans. The availability of reproducible and relevant experimental corneal immune reactions will facilitate the development and testing of new therapeutic strategies for controlling or preventing deleterious corneal immune reactions.