Comparison of antigen-specific T cell responses in autoimmune MRL/Mp-1pr/1pr and MRL/Mp-+/+ mice

The MRL-1 mouse develops severe autoimmune disease characterized by high titers of autoantibodies at an early age (3 to 5 mo). The congeneic MRL-n mouse, which differs only in the lymphoproliferative (lpr) gene, exhibits no such pathologic or serologic abnormalities at the same age. We examined antigen-specific T cell responses in the MRL-1 mouse and compared them to age- and sex-matched MRL-n controls. We found broad defects in these responses in the MRL-1 mouse; an inability to generate primary allospecific and hapten-specific cytolytic T lymphocytes (CTL), secondary hapten- and virus-specific CTL, as well as a deficient proliferative response to hapten and natural antigens and a weak delayed-type hypersensitivity response were demonstrated. Our data furthermore suggest a lack of interleukin 2 (IL 2) acceptor sites in the proliferating T cell, while suggesting no such lack on CTL precursors. In fact, the deficient CTL responses in MRL-1 mice can be restored to levels seen in MRL-n by the in vitro addition of IL 2. The implications of these findings and the possible explanations for the relative deficit in helper function in the MRL-1 mouse are discussed.