Intrathecal immune responses in mumps meningitis patients

The in vitro 3H-thymidine incorporation of peripheral blood (PB) and cerebrospinal fluid (CSF) lymphocytes from 11 mumps meningitis patients was studied after stimulation with non-specific mitogens and microbial antigens. Although corresponding viral antibodies were always found in the CSF of seropositive patients by a sensitive radioimmunoassay, their intrathecal synthesis was directed mainly against mumps virus. Most of the patients had PB lymphocytes that reacted on stimulation with phytohaemagglutinin (PHA) or pokeweed mitogen (PWM), but a smaller number of them had reactive CSF cells. Only four patients showed stronger responses to PHA in the CSF than in PB. Most patients had mumps-reactive lymphocytes in PB but only two of them in the CSF. In contrast, these patients more often had increased CSF cell reactivity when tested with purified protein derivative, measles, and herpes simplex virus antigens. The results could not be explained by a damaged blood-brain barrier alone but may reflect the immunological status of the brain compartment in these patients.