Initial phase of an inflammatory reaction in testis caused by experimental testicular autoimmunity in the Nile tilapia, Oreochromis niloticus.

Abstract

In order to study the pathogenesis of the testicular autoimmunity induced by the immunization with allogeneic testis homogenate (ATH) mixed with Freund's complete adjuvant (FCA) in the Nile tilapia Oreochromis niloticus, the initiation of inflammatory reactions in the testis was ultrastructurally investigated and seminal plasma was analyzed for presence of autoantigens. In the seminal plasma, mainly 120 kD and 80 kD autoantigens were identifiable by Western blotting with tilapia antisperm autoantibody. Eight weeks after injection with FCA, globate structures, possibly originating from FCA, were large and distended the interstitium where the inflammatory reactions were more frequently recognizable. The globate structures may be one of causes to break the blood-testis barrier, and the inflammatory reaction may be due to the leakage of soluble autoantigens from the lumen. In the interstitium, several kinds of immunocompetent cells formed masses which were mainly composed of lymphocytes, macrophages, eosinophils and plasma cells. We suggest that the inflammatory reactions in fish caused by the immunization with ATH+FCA are initiated by sensitization of the immunocompetent cells with testicular autoantigens, the 120 kD and 80 kD autoantigens in the seminal plasma are two of them, leaking from the lumen because of the provable effect of FCA. These initial reactions were then amplified by cellular and humoral immunity.