Regulation of experimental autoimmune orchitis by the presence or absence of testicular antigens during immunological development in SCID mice reconstituted with fetal liver cells.

Severe combined immunodeficient (SCID) mice were immunologically reconstituted by the transfer of fetal liver cells (FLC) of BALB/c mice (SCID-FLC mice). In peripheral blood (PB) of SCID-FLC mice, B and T cells started to appear 2 and 5 weeks, respectively, after the transfer of FLC, and had attained normal levels by 7 weeks. Orchidectomy and transplantation of testis under the kidney capsule were conducted at various stages of immunological maturation, and the induction of experimental autoimmune orchitis (EAO) was performed after immunological maturation in SCID-FLC mice. The experimental system was used to establish that the presence of testicular antigens in the early stage of immunological development influences the induction of EAO; grade of EAO was reduced in the presence of the antigens, and enhanced in their absence. In other words, the existence of self tissue antigens in the early stage of immunological development was essential for proper establishment of tolerance to the self tissue. These findings suggested that the SCID-FLC mouse is a suitable model with which to analyse the interaction between self antigens and cells of the developing immune system, which is otherwise observed only in the fetal or perinatal stage in experimental animals.