Central nervous system immunity associated with clinical outcome in acute encephalitis

To search for useful laboratory measures of central nervous system (CNS) immunity that may provide an accurate prognosis or clues regarding treatment choice, cerebrospinal fluid (CSF) samples were obtained from 14 consecutive patients with acute encephalitis during acute as well as convalescent or chronic stages, and then examined for surface antigen expressions by lymphocytes and the presence of antineuronal tissue antibodies as well as the levels of IgG-related parameters and proinflammatory cytokines, including IL-2, IL-6, IFN-gamma, and tumor necrosis factor-alpha (TNF-alpha). Seven patients with aseptic viral meningitis served as nonencephalitic controls. Eight of the 14 acute encephalitis patients recovered fully, and reductions in the percentages of CD4(+)CD29(+) helper inducer T cells and IL-2 receptor-positive CD4(+) cells were associated with early recovery and favorable outcome, respectively, whereas a low percentage of CD4(+)CD26(+) memory T cells during an acute stage was associated with an unfavorable outcome following adjunctive intravenous corticosteroid treatment. Further, three of the four encephalitis patients who exhibited autoantibodies had a poor prognosis. These findings suggest that CNS immunity status has an effect on prognosis, while flow cytometric analyses of CSF CD4(+) helper T cell subsets may serve as effective means of assessment.