T lymphocytes in cerebrospinal fluid from patients with neurological diseases.

T lymphocytes were determined according to their ability to form rosettes with sheep erythrocytes, in cerebrospinal fluid (CSF) from 120 patients, and in peripheral blood from 59 patients. Normal CSF contained 74.9 +/- 9.6% T lymphocytes. Increased T lymphocyte percentage was found in CSF from patients with active multiple sclerosis (MS), and Guillain-Barré syndrome, as well as the 2 patients with retrobulbar neuritis and the 1 with subacute sclerosing panencephalitis. Patients with stable MS showed no significant change in CSF T lymphocyte percentage. CSF from patients with viral meningo-encephalitis or meningo-radiculitis had a decreased T lymphocyte percentage. This decrease was also found in the 2 patients with malignant disease and the 2 with presenile dementia. An exceptionally low CSF T cell count (5%) was found in 1 patient with cerebellar ataxia.