Characteristics of poxvirus-induced meningitis: virus-specific and non-specific cytotoxic effectors in the inflammatory exudate.

Mice injected intracerebrally with a sublethal dose of vaccinia virus develop severe meningitis. The number of inflammatory cells in cerebrospinal fluid (CSF) increases approximately threefold each day for 3 to 7 days after intracerebral challenge, subsequent to which samples can no longer be obtained because the cisterna magna is obliterated owing to brain swelling. Examination of this inflammatory exudate during the later stages of this pathological process shows evidence of both cytotoxic T lymphocyte (CTL) function and the presence of Lyt1+ and Lyt2+ cells on days 6 and 7. In addition, potent non-T-cell (Lyt2-) cytotoxic activity is found in CSF taken from younger (12 weeks) mice as early as after day 3 and is still present on day 6. The level of non-T-cell-mediated cytotoxicity in CSF on day 5 or 6 (but not day 3) is considerably decreased in animals that were also given a large dose of virus intravenously to maximize T-cell stimulation in lymphoid tissue, and the extent of CTL activity is concomitantly increased. The diminution of non-specific cytotoxic function does not seem to reflect simple dilution in the presence of excess virus-immune T cells.