Phenotypic and functional characterization of CD8(+) T lymphocytes from the central nervous system of rats with coronavirus JHM induced demyelinating encephalomyelitis

Intracerebral infection of Lewis (LEW) inbred rats with the neurotropic strain of the murine coronavirus JHM (JHMV) frequently results in a monophasic paralytic disease. In contrast, infection of frown Norway (BN) inbred rats does not lead to clinical disease. Previous findings indicated that in both rat strains brain-infiltrating leukocytes consisted mainly of CD8(+) T lymphocytes. Here, we phenotypically as well as functionally characterised this T cell subset after isolation from the central nervous system (CNS). Using JHMV-infected target cells, MHC class I restricted, cytotoxic T lymphocytes were demonstrated to be present in the leukocyte fraction from the CNS of both, susceptible LEW and disease-resistant BN rats. However, compared to infected, but healthy BN rats, diseased LEW rats generated an enhanced cytotoxic immune response which became most prominent at the maximum of neurological disease. Recently published observations from our laboratory demonstrated a strong virus-specific antibody response in the CNS of EN rats. In LEW rats, however, the response was delayed and of low magnitude. This suggests, that consequences of cytotoxic T lymphocyte action in JHMV-infected CNS tissue largely depend on the efficacy of an accompanying virus-specific humoral immune response.