Intrathecal nonspecific immunoglobulin synthesis in syphilitic infection

Intrathecal Ig synthesis is one of the characteristic laboratory features of neurosyphilis (caused by Treponema pallidum subspecies pallidum able to affect the central nervous system (CNS), but a persisting pathogen-driven immune response is problem of scar effect. This long-term Ig production within the CNS compartment even after timely and proper treatment remains unexplored. We hypothesized that a long-term current chronic inflammation in the CNS caused by syphilitic infection can be a trigger of nonspecific humoral immune response and the scar effect may result from non-specific B cell activation within the CNS in the absence of antigens. The MRZ reaction is a laboratory tool for detection of intrathecal nonspecific humoral immune reaction, which is poorly investigated in syphilis patient. The MRZ reaction (MRZR) is used as a marker of intrathecal nonspecific humoral immune response and is composed of the three antibody indices (AI) against neurotropic viruses: measles, rubella and varicella zoster virus. A positive MRZR, defined as an elevated AIs (> 1.5) against at least one or more viral agents, confirms diagnosis of a chronic or autoimmune disease involving CNS recently declared as a highly specific marker of multiple sclerosis. Insufficient data on neuroinfections motivated us to examine a hypothesis that a long-term chronic inflammation within the CNS compartment caused by syphilitic infection may be a trigger of intrathecal nonspecific humoral immune response. We assessed prevalence of positive MRZR in 147 patients with later-stage syphilis seropositive for MRZ viruses. Study group included 43 patients with first-time diagnosed neurosyphilis, 16 patients with a follow-up visit after neurosyphilis treatment, 88 patients with excluded neurosyphilis. There were no significant differences between categories of patients examined, and presence of positive MRZR was not associated with any demographic, clinical and laboratory characteristics. To sum up, our study (n = 147) showed that 27 patients (18%, 95% CI: 12–25% ) were positive for intrathecal Ig production against one, two or three of the M, R, Z viruses, and bi- and tri-specific MRZR was present in 7 of 147 patients (5%, 95% CI: 2–10%). The data obtained evidence that frequency of the MRZR for syphilitic infection matches that of found in general population and a long-term current syphilitic infection affecting CNS seems to not be a trigger of a nonspecific intrathecal immune response. Among our patients, we also selected 43 patients with previously treated syphilitic infection without any neurological symptoms and excluded neurosyphilis diagnosis, so these patients can be considered as an apparently healthy group.