Specificity of immunoglobulins synthesized within the central nervous system in neurosyphilis

Cerebrospinal fluid from four patients with serologically and clinically verified neurosyphilis contained oligoclonal bands when analysed by isoelectric focusing. By antiserum immunofixation these bands consisted by IgG, and by antigen immunofixation and autoradiography the bands were shown to contain treponemal antibodies. Treponemal antibodies synthesized within the CNS were also detected in polyclonal CSF IgG fractions in two of the patients. In one patient with neurosyphilis followed over 2.5 years, local synthesis of IgM and IgA disappeared within 1 year after treatment, while IgG synthesis persisted. In this patient, besides treponemal antibodies, antibodies against herpes simplex virus were also detected in oligoclonal and polyclonal IgG fractions of CSF. The presence of treponemal antibodies synthesized within the CNS was identified in 2 of 16 controls with negative serological tests for syphilis. This might reflect a previous contact with apathogenic treponemes, and the intrathecal antibody synthesis might be a result of an unspecific activation of memory lymphocytes in CNS.