Tetanus toxoid reactive T lymphocytes in the cerebrospinal fluid of multiple sclerosis patients.

Cerebrospinal fluid (CSF) lymphocytes of 6 multiple sclerosis (MS) patients were cultured with tetanus toxoid (TT) and irradiated autologous antigen presenting cells (APC) followed by propagation of the responding T-cells in interleukin-2 containing medium. TT-reactive cell lines were recovered from 4 of the 6 CSF samples, even though the patients had not been TT booster immunized in recent years. These findings suggest an active circulation of antigen reactive lymphocytes from the systemic immune compartment(s) into the CSF even without recent activation by booster immunization. Since immune reactions to TT are very unlikely to be pathogenic in MS, these findings also indicate that presence of CSF lymphocytes reactive to a particular antigen does not necessarily imply a causal role.