Split tolerance of Thl and Th2 cells in tolerance to Theiler's murine encephalomyelitis virus

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Abstract
Theiler's murine encephalomyelitis virus (TMEV) produces a chronic, inflammatory demyelinating disease in susceptible mouse strains that is used as a model for multiple sclerosis. Because disease susceptibility correlates temporally with the development of virus‐specific delayed‐type hypersensitivity (DTH) responses, we studied methods and mechanisms by which virus‐specific DTH could be specifically inhibited. The intravenous injection of UV‐inactivated TMEV coupled to syngeneic splenocytes via a carbodiimide linkage (TMEV‐SP), prior to immunization, induced a significant degree of tolerance in virus‐specific helper (Th) cells as determined by decreased DTH and T cell proliferative responses, and decreased interleukin (IL)‐2 and interferon (IFN)‐Y protein and mRNA levels. In contrast to the reduced levels of Thl‐specific lymphokine mRNA levels, IL‐4‐specific mRNA levels in response to virus stimulation were not affected in tolerant mice. Surprisingly, the total anti‐TMEV antibody response in DTH tolerant mice was enhanced 20‐100‐fold over sham‐tolerized controls and was composed of reduced levels of anti‐virus IgG2a, but dramatically increased levels of anti‐virus IgGl. The “split‐tolerance” was antigen specific, dependent on the concentrations of TMEV and carbodiimide used in the coupling procedure, and varied with the number of coupled syngeneic splenocy tes administered. The fixative effects of carbodiimide on antigen‐presenting function were necessary for the induction of DTH tolerance with TMEV‐SP, since intravenous administration of virus coupled to splenocytes via a biotin‐avidin linkage led to enhanced virus‐specific antibody responses, but was unable to inhibit DTH unless concomitantly fixed with carbodiimide. Collectively, the data indicate that Thl cells (mediating DTH, IL‐2 and IFN‐γ production, and helper function for IgG2a production) were specifically anergized, with concomitant stimulation of Th2 cells (producing IL‐4 and mediating helper function for IgGl antibody production).