Experimental allergic orchitis in mice: IV. Preliminary characterization of the major murine testis specific aspermatogenic autoantigen(s).

Active experimental allergic orchitis (EAO), characterized by inflammation of the testes (autoimmune orchitis), aspermatogenesis, epididymitis and vasitis was induced in mice using a panel of tissue antigens as immunogens. Immunization with allogeneic murine tissue homogenates emulsified in complete Freund's adjuvant (CFA) accompanied by the injection of pertussigen revealed that only adult murine testicular and epididymal homogenates are capable of eliciting murine EAO. All other tissue antigens studied including prepubertal mouse and epididymal homogenates failed to elicit significant disease. Immunization with xenogeneic testicular antigens also failed to elicit significant disease indicating that the major murine aspermatogenic autoantigen(s) is also highly species specific. Sensitization with allogeneic mouse testicular homogenates (MTH) from different disease resistant strains was for the most part no less potent in inducing significant disease than was immunization with mouse testicular homogenates from disease susceptible strains. However, testicular homogenates from NZB/B1NJUnm and MRL/MpJ-/+Unm mice were significantly less potent at inducing autoimmune epididymitis as compared to other strains, indicating possible interstrain differences in the immunogenicity of the aspermatogenic autoantigen(s) relevant to eliciting epididymitis. Attempts at solubilization and purification of the major murine aspermatogenic autoantigen(s) utilizing techniques employed for the purification of aspermatogenic autoantigens such as AP3 from guinea pig (GP) testes were unsuccessful. Additional extraction procedures resulted in solubilization of the relevant autoantigen(s) only after reduction in the presence of 6 M guanidine hydrochloride. These data suggest that: (1) there may be a much more limited number of aspermatogenic autoantigens in murine testes as compared to GP testes; (2) the disease inducing determinant(s) may be expressed as either a sequential antigenic determinant(s) or as an antigenic determinant(s) in the carbohydrate portion of a glycoprotein or glycopeptide; and (3) the disease inducing autoantigen(s) may be present in situ in a highly insoluble form requiring active processing within the target organ in order to generate soluble antigen capable of being seen by immune reactants.