An acute form of transferred experimental allergic encephalomyelitis was induced by injection of activated, myelin basic protein-specific T cell line lymphocytes. The course of the disease as a function of the dose of cytotoxic cells was investigated, and the effect of i.p. and i.v. application of methotrexate on mortality and morbidity was determined. Depending on the time of administration, beneficial therapeutic effects could be seen as early as 1 week. Survival of animals that had received a lethal dose of 15 to 20 X 10(6) cells/kg proved to be the most valuable parameter. T lymphocyte line-mediated experimental allergic encephalomyelitis is a predictable acute central nervous system model disease that does not require antigen depots or cell donor animals.