Experimental allergic orchitis induced by unilateral intratesticular bacterial infection in guinea-pigs.

Inoculation of 1 X 10(3) viable Listeria monocytogenes into unilateral testis induced pathological changes in the contralateral testis and epididymis in guinea-pigs. Because L. Monocytogenes was not detected in the contralateral testis, liver or spleen during the period of the experiment, that is, bacterial growth was limited to the inoculated site, the pathological changes in the contralateral testis may be due to autoimmune mechanisms, but not due to bacterial inflammation. The pathological changes in our system were similar to those observed after the injection of testicular antigen in Freund's complete adjuvant. Delayed-in-onset erythematous skin reaction against testicular antigen and antisperm antibody in sera were detected in the guinea-pigs. The animal model in our system is a new one in which experimental autoimmune orchitis is induced by bacterial infection.