In vitro induction of experimental autoimmune orchitis: characterization of a primary T lymhocyte response against testicular self antigens.

Lymphocytes from normal, young adult rats were autosensitized in vitro against trypsin-dissociated autologous testis cells. The autoimmune response had been assayed both by determination of the lymphocyte proliferation, using a (3H)thymidine incorporation test, as well as by determination of their specific cytostatic activity against monolayer-forming testis cells which was measured in a terminal 51Cr uptake assay. The actively responding cells in this system are T lymphocytes. Non-T cells can exert additional, non-specific cytostasis. The immune specificity of the in vitro experimental autoimmune orchitis (EAO) has been demonstrated on two levels. First, the responding T lymphocytes were found to specifically adhere around cells from one particular testis subpopulation which morphologically resemble Sertoli cells. The rosetting lymphocytes respond only to testicular self antigen, but not to allogeneic lymphocytes. Second, specificity to the effector T lymphocytes was revealed in transfer experiments. Autosensitized EAO effector T cells cytostatically affected only major histocompatibility gene complex (MHC)-compatible testis cells. Their reactivity against MHC-different testis cells or MHC-compatible nontesticular fibroblasts was significantly decreased which suggests both tissue as well as MHC specificity of the EAO response.