Autoreactive cytotoxic T cells in mice are induced by immunization with a conserved mitochondrial enzyme in Freund's complete adjuvant

Standard methods to generate autoimmune reactions in mice, by immunization with antigens emulsified with adjuvants, stimulate strong helper (CD4) T-ce ll and antibody responses but are not reported to induce cytolytic CD8 T ce lls. The aim of this study was to assess whether specific autoreactive CD8 T cells could be readily generated after immunization with a 'weak' autoant igen in adjuvant. Mice were immunized intraperitoneally three times with th e E3 subunit of the mitochondrial 2-oxoacid dehydrogenase enzyme complexes (dihydrolipoamide dehydrogenase) emulsified with Freund's complete adjuvant . Splenic and lymph node lymphocytes were harvested after 14 days for in vi tro functional studies. T lymphocytes were tested for proliferative respons es and cytotoxicity against antigen-loaded isogeneic target cells. An autor eactive cytolytic T lymphocyte (CTL) response was detectable only after the in vitro restimulation of lymphocytes with E3 antigen-loaded syngeneic spl enocytes. These CTL were identified as H-2-restricted CD8(+) T cells. A pro liferative response to E3 was demonstrable against antigen-pulsed syngeneic splenocytes. Immunized mice also generated strong antibody responses to E3 . Liver histology showed portal infiltrates interpreted as a response of th e liver to a non-specific immunological stimulus. It is concluded that auto reactive cytolytic T cells can be generated experimentally upon appropriate stimulation of the immune system, and can be identified in vitro upon rele ase from the controlling mechanisms that are likely to regulate them in viv o.