Cytotoxic T cells isolated from the central nervous systems of mice infected with Theiler's virus

Intracerebral inoculation of resistant mice (C57BL/10SNJ) with Theiler's murine encephalomyelitis virus (TMEY) results in acute encephalitis followed by subsequent clearance of virus from the central nervous system (CNS). In contrast, infection of susceptible mice (SJL/J) results in virus persistence and chronic immunemediated demyelination. Both resistance and susceptibility to TMEV-induced disease appear to be immune mediated, since immunosuppression results in enhanced encephalitis in resistant mice but diminished demyelination in susceptible mice. The purpose of these experiments was to determine whether anti-TMEV cytotoxic T lymphocytes (CTLs) are generated during acute and chronic TMEV infection. Nonspecific lectin-dependent cellular cytotoxicity was used initially to detect the cytolytic potential of lymphocytes infiltrating the CNS irrespective of antigen specificity. Using TMEV-infected targets, H-2-restricted TMEV-specific CTLs of the CD8⁺ phenotype were demonstrated in lymphocytes from the CNS of susceptible and resistant mice, arguing against the hypothesis that the ability to generate CD8⁺ CTLs mediates resistance. In chronically infected SJL/J mice, TMEV-specific CTL activity was detected in the CNS as late as 226 days postinfection. These experiments demonstrate that virus-specific CTLs are present in the CNS during both acute and chronic TMEV infection. Anti-TMEV CTLs in the CNS of chronically infected SJL/J mice may play a role in demyelination through their ability to lyse TMEV-infected glial cells.