Demonstration of locally synthesized immunoglobulin M antibodies to Treponema pallidum in the central nervous system of patients with untreated neurosyphilis.

Immunoglobulin M (IgM) antibodies to Treponema pallidum (TP) in serum and cerebrospinal fluid (CSF) can be evaluated quantitatively using a recently introduced enzyme-linked immunosorbent assay (ELISA). In 19 patients with untreated neurosyphilis, local synthesis of TP-specific IgM antibodies within the central nervous system (CNS) was demonstrated by estimation of the CSF/serum ratio of the TP-IgM-ELISA titer/mg total IgM. The TP-specific IgM antibody levels/mg total IgM in the CSF were between 3- and 75-fold higher than those in the corresponding serum of the same patients. Patients with untreated syphilis but without CNS involvement showed equal amounts of TP-specific IgM antibody levels/mg total IgM in CSF and serum, and served as controls.