[Local production of antibiotics in the CNS as a specific parameter in the immunologic diagnosis of neurosyphilis].

Concentrations of albumin and total IgG as well as TPHA-IgG antibody titres have been determined in pairs of serum and cerebrospinal fluid of 280 syphilitic patients with or without clinical symptoms of neurosyphilis. As the ratio of the TPHA-IgG titre per mg total IgG in cerebrospinal fluid and serum (CSF-TPA ratio) has been found to be a parameter for the local synthesis of treponemal IgG antibodies in the CNS, there must be assumed a participation of the CNS in syphilitic infection. In patients without participation of the CNS on the treponemal infection, the average CSF-TPA ratio is 1 with a range between 0.5 and 2.0. A local synthesis of treponemal IgG antibodies in the CNS is indicated by an increased ratio even in case of dysfunction of the blood-brain-barrier. A decreased ratio points out to a disorder of the CNS independent of te syphilitic infection. In patients with neurosiphilis having been cured ("burnt out") several decades ago the CSF-TPA ratio may return to normal possibly associated with a tissue scar in the CNS and corresponding neurological disorders.