Recent studies in our laboratory demonstrated that the histological responses of an out-bred and inbred strain of mouse, to bacterial challenge with Pseudomonas aeruginosa into the anterior chamber of their eyes, were strikingly dissimilar. The out-bred strain spontaneously recovers, with no permanent damage, whereas the inbred strain suffers irreversible damage leading to blindness. Therefore, these studies suggested that infection with P. aeruginosa would be an appropriate experimental model for studying the natural defense mechanisms of the eye. The project will be divided into two major areas of research. They encompass the following: 1) an ultrastructural study of the eye of various mouse strains (both inbred and out-bred) before, during, and after bacterial challenge to the eye. These studies will utilize light, electron and scanning microscopy and emphasize the histopathological and cellular responses of infected animals' eyes. Normal mice, thymectomized mice, X-irradiated mice and antineoplastic drug-treated mice (both inbred and out-bred) will be included in the ultrastructural and histological studies and 2) a comprehensive study of the natural defense mechanisms of the eye to Pseudomonas challenge in the above mentioned mice will be performed. This study will include attempts to identify and quantitate the genetic, tissue, cellular and humoral factors which may play a role in the outcome of the eye infection.