Breeding for fine black fur has generated a colony of mink wherein 20-30% of the males are infertile. Two clinical groups are distinguishable: one being infertile from the start (primary
infertility), and the other infertile after one or more years of fertility (secondary fertility). Although the etiology of primary
infertility is unknown, the available data indicate that secondary
infertility is associated with an
autoimmune disease of the testis. Thus, male mink with secondary
infertility have (a) higher prevalence and levels of anti-sperm antibody when compared with animals with primary
infertility, and the antibody prevalence varies with fur color; (b) severe monocytic
orchitis (47%) and/or aspermatogenesis (75%) with negative cultures for bacterial, fungal,
mumps, or Coxsackie B viral organisms; (c) massive and extensive granular deposits of mink
IgG and/or C3 (71%), typical of
immune complexes, along the basal lamina of seminiferous tubules; (d) testes that when eluted with
buffer or low pH yielded
IgG that was 10-fold enriched in anti-sperm antibody activity as compared with serum
IgG; and (e) no immunopathologic evidence of
Aleutian mink disease. Although the sperm
antigen-antibody complexes in the testis may be important as a pathogenetic mechanism of the
testicular disease, there is no correlation between fluorescent anti-sperm antibody detection in the serum and the infertile state. The infertile black mink is a new model of
infertility associated with naturally occurring
autoimmune disease of the testis.