[Meningitis associated with tsutsugamushi disease--detection of intrathecal interferon-gamma synthesis and lymphocyte subsets in blood and CSF].

We report a case of meningitis associated with tsutsugamushi disease. The lymphocyte subpopulation study of peripheral blood revealed a reversed CD4/CD8 ratio (0.14), an increased number of activated T cells and an elevated cytotoxic T cell activity. In cerebrospinal fluid (CSF), the CD4/CD8 ratio was much higher (0.84) and activated T cells were less prevalent than in blood. These pictures of lymphocyte subsets were characteristic and different from that of viral meningitis. We also verified an elevation of interferon-gamma levels in CSF as well as in serum and intrathecal interferon-gamma synthesis while the specific antibody production in CSF compartment was not demonstrated. T cell-mediated immunity many play an important role not only systemically but also locally in the central nervous system in tsutsugamushi disease.