BACTERIAL-INFECTION OF THE TESTIS LEADING TO AUTOAGGRESSIVE IMMUNITY TRIGGERS APPARENTLY OPPOSED RESPONSES OF ALPHA-BETA AND GAMMA-DELTA T-CELLS

The mechanisms that lead to the breakdown of self-tolerance and testis -specific immune reactivity in the murine orchitis model are understoo d only in part. We investigated the histopathologic and immunologic co nsequences of a unilateral bacterial (Listeria monocytogenes) infectio n of the testis. Both infected and contralateral sides of this bilater al organ suffered severe inflammatory responses despite a conspicuous absence of bacteria in the contralateral tissue. Also, in both testicl es, T cell populations increased, involving both alpha beta and gamma delta T cell subsets. Concomitant with the bilateral orchitis, testis- specific delayed type hypersensitivity and Ab responses developed. Ab depletion experiments indicated that in this orchitis model, as in oth ers, alpha beta T cells are initiators of the autoaggressive reactivit y. In contrast, Ab depletion of gamma delta T cells accelerated the in flammatory response in both testicles, suggesting a regulatory role fo r this type of T cells in both infection-induced and autoimmune orchit is.