IMMUNOREACTIVITY OF THE CENTRAL-NERVOUS-SYSTEM IN CATS WITH A BORNA DISEASE-LIKE MENINGOENCEPHALOMYELITIS (STAGGERING DISEASE)

The inflammatory cell composition and the expression of major histocom patibility complex (MHC) antigens in the central nervous system (CNS) of 13 cats with a spontaneous, Borna disease-like meningoencephalomyel itis (staggering disease) was investigated by immunohistochemistry wit h a panel of monoclonal and polyclonal antibodies. T lymphocytes were the predominating inflammatory cells within the adventitial space. CD4 (+) T cells were more abundant than CD8(+) T cells. Scattered IgG-, Ig A- and IgM-containing cells were found in the adventitial space and su rrounding neuropil, often adjacent to neurons. There was a markedly in creased MHC class II expression in cells morphologically resembling mi croglia. In several cars, Borna disease virus specific antigen was det ected, but only in a few cells, mainly of macrophage character. Our fi ndings indicate a long-standing inflammatory reaction in the CNS of ca ts with staggering disease, possibly triggered and sustained by a pers istent viral infection.