This review summarizes recent studies on the mechanisms of self-tolerance and
autoimmune disease pathogenesis based primarily on the murine ovarian
autoimmune disease models. The ovarian
autoimmune disease was induced experimentally by three approaches: (1) transfer of normal T cells into syngeneic athymic nu/nu mice, (2) neonatal
thymectomy, or (3) immunization with a well-defined
peptide from the ovarian
antigen, ZP3. Self-reactive T cells with capacity to elicit
autoimmune oophoritis and autoimmune
gastritis are not deleted in the neonatal or adult thymus. In the adult spleen, T cells are not pathogenic until regulatory T cells have been depleted. Thus the balance of activity between pathogenic T cells and regulatory T cells appears to determine the tolerance status of the host to
self-antigens responsible for these
autoimmune diseases. Murine
autoimmune disease of the ovaries was found to occur through two independent pathways. The first is by depletion of regulatory T cells, as created by
thymectomy within 4 days after birth. Alternatively, pathogenic T cells can be activated through molecular mimicry at the level of T cell
peptide. This appears to depend on the sharing between non-ovarian and ovarian
peptides of critical
amino acid residues required for activation of pathogenic T cells. Finally, when T cells that recognize the ZP3
peptide are activated, endogenous ovarian
antigens can spontaneously stimulate B cells to produce
antibodies that react with ZP3 domains outside the immunizing T cell
peptide.