The Objective of the proposed study is to elucidate the molecular and cellular immunological responses at the local site of infection during the course of acute and chronic chlamydia infection in the salpinx primate pocket model. The experimental approach will generate information about immune cell subsets with cytokine assays, immunohistochemical data, and mRNA expression from the tissues representing different stages of chlamydia infection to ascertain their role(s) in scarring and fibrosis associated with tubal infertility. The specific aims are: i) Phenotype the principal components of the local inflammatory infiltrate including subsets of T and B cells; 2) Identify cytokine expression within acute and chronic lesions; 3) characterize the function and specificity of lesion lymphocytes (T and B cell subpopulations) and peripheral blood, and evaluate their roles in the local inflammatory process; and 4) Isolation of T cell lines and clones that are specific for Chlamydia trachomatis. These studies will contribute not only to the understanding of the molecular and cellular basis of the inflammatory response to C. trachomatis salpingitis, but also to the development of effective means of treatment and prevention of infertility and ectopic pregnancy.