The protective role of thymus-derived lymphocytes in arbovirus-induced meningoencephalitis.

The inflammatory response in mouse brain and the elimination of virus from the brain following intracerebral inoculation of a group A arbovirus has been shown to be T-cell dependent. Virus persists in the brain of T-cell depleted mice, and inflammation is depressed. Virus persists in the brain of T-cell depleted mice, and inflammation is depressed. Inflammation is restored by transfer of immune cells but not by immune serum, and the transferred cells are effective in reducing virus titres in the absence of circulating antibody. Transferred antibody is not efficient in protecting infected mice. The cells that restore inflammation can come from mice immunized with a group A arbovirus of the same subtype but not from mice immunized with more distantly related viruses. Macrophages may be important effector cells working in collaboration with T cells.