[Immunology of neurosyphilis: intrathecal synthesis of Treponema pallidum-specific IgG and IgM antibodies].

Due to uncharacteristic symptoms of central nervous system (CNS) alterations during Treponema pallidum (TP) infection, the exact diagnosis of neurosyphilis has become more and more difficult. Particularly, there is a lack of sufficiently specific and sensitive assays for the demonstration of intrathecal synthesis of TP-specific immunoglobulins. TP-specific IgG or IgM class antibodies were estimated quantitatively in serum and cerebrospinal fluid (CSF) of 302 syphilitic patients by a modified enzyme immunoassay (ELISA), and antibody concentrations were quantitated as ELISA units per mg total IgG or IgM. In 197 of 237 patients with neurosyphilis an intrathecal synthesis of TP-specific IgG or IgM could be demonstrated by a 3- to 450-fold higher antibody concentration in the CSF than in the corresponding serum. In contrast, 65 patients without CNS involvement on the infection did not show any difference in the antibody concentration of CSF and serum. Thus, the diagnosis of neurosyphilis respectively the exclusion of CNS participation on the TP infection on an immunological base has become possible.