Intrathecal IgA synthesis in neurosyphilis

Intrathecal immunoglobin synthesis and its role in patients with neurosyphilis

Background

Intrathecal protein synthesis (ITS) occurs in various central nervous system disorders, but few quantitative studies have focused on ITS for neurosyphilis (NS) in southwestern China. We made a study to quantitatively assess the ITS in patients with NS and to investigate the association between ITS and the stages of NS.

Methods

CSF-serum specimen pairs from 142 patients (66 NS and 76 non-NS/syphilis) were collected for routine CSF and serum tests. The NS group was divided into slight and severe subgroups according to the NS stages. Three formulas for the quantitative determination of the intrathecal synthesis were calculated to characterize the specimens, including the Ig index (Q_Ig/Q_alb), Ig extended index (Ig_EI), and intrathecally synthesized fraction (IgIF) using the hyperbolic function. The role of QTPPA/QIgG as an antibody index (AI = Q specific Ig/QIgG) was also explored.

Results

Sero_TRUST titres (1:16, 1:1-1:256), sero_TPPA titres (1:163840, 1:1280-1:1310720), total protein (MTP), and CSF_Igs (p < 0.05) were found to be significantly elevated in the NS group. Intrathecal Ig synthesis can be identified using all three formulas in the NS group. The pattern of Ig intrathecal synthesis was IgIF-G (48.62%) > IgIF-A = IgIF-M (p < 0.05), with the dominant intrathecal fraction being IgG (median, 48.62%), which was also verified by Q_IgG> Q_alb> Q_IgM = Q_IgA. In the slight NS group, the intrathecal fractions of IgM (>0 in 4 out of 20 cases) and IgG (>0 in 16 out of 20) were lower than the intrathecal fractions of IgM (>0 in 19 out of 35 cases) and IgG (>0 in 33 out of 38) in the severe group (p < 0.05). The area under the curve (AUC) of the CSF_TPPA antibody index was 0.867 (0.792, 0.922), with an optimal cutoff point of 0.81, providing a sensitivity of 88.91% and specificity of 84.62%.

Conclusion

Although the intrathecal synthesis pattern is IgG dominant in patients with NS, brain-derived IgM and IgA can also be found. Moreover, intrathecal IgM and IgG were associated with a parenchymatous type of neurosyphilis. Syphilis-specific antibodies are a new potential tool for NS diagnosis.

Assessing cerebrospinal fluid abnormalities in neurosyphilis patients without human immunodeficiency virus infection

Neurosyphilis (NS) caused by Treponema pallidum (T. pallidum) subspecies pallidum, can affect the central nervous system during any stage of the disease. To assess several laboratory parameters for NS diagnosis, we performed a case control study on 42 hospitalized NS patients negative for human immunodeficiency virus (HIV) and 40 syphilis/non-NS patients, excluding NS patients at Xiamen Zhongshan Hospital from June 2010 to June 2011. Multivariate logistic regression model showed that the cerebrospinal fluid white blood cell (CSF-WBC, P = 0.009) levels, the CSF-LDH (P = 0.006) levels, the albumin quotient (P = 0.009) and the IgA index (P = 0.042) were independently associated with high risk of NS. The receiver operator characteristic (ROC) curve analysis revealed that the optimal cut-offs were 10 × 106 cells/L for the CSF-WBC concentration, 19.3 U/L for the CSF lactate dehydrogenase (LDH) concentration, 7.08 for the albumin quotient, and 0.14 for the IgA index. Combining the CSF-WBC level, the CSF-LDH level, the albumin quotient and the IgA index increased the NS diagnosis sensitivity to 97.6%. T. pallidum particle agglutination (TPPA) index significantly correlated with the CSF-WBC (r = 0.453, P = 0.000), the IgA index (r = 0.446, P = 0.000), the albumin quotient (r = 0.262, P = 0.017), and the CSF-LDH (r = − 0.278, P = 0.012), respectively. In addition, there were correlations between the CSF-WBC and the IgA index (r = 0.329, P = 0.003), and between the CSF-WBC and the albumin quotient (r = 0.306, P = 0.005). Our results indicated that simultaneous testing of CSF-WBC levels, albumin quotient, IgA index and CSF-LDH can help predict the likelihood of NS in HIV-negative patients.

A patient with multifocal tabetic arthropathy: a case report and review of literature

A 55-year-old man presented with a painless destruction of multiple joints and neurologic deficits. He was admitted with a painless pyogenic arthritis of the right ankle. Four years earlier, he had experienced instability of the right knee after an inexplicable, progressive but painless destruction of the joint. Radiographs showed erosive changes at the smaller joints of both hands and the left foot, as well as deformation and destruction of the right foot. Results from both treponemal and nontreponemal serologic test were positive in blood. The Treponema pallidum particle agglutination index was positive in the cerebrospinal fluid. Tabetic arthropathy was diagnosed.Tabetic arthropathy is a manifestation of neurosyphilis. Because syphilis is known as "the great imitator" and tertiary syphilis is rare, recognizing the disease is the biggest challenge for health care providers. Symptoms may mimic any other disease, and many different medical specialists may be faced with these patients, or as Sir William Osler put it: "He who knows syphilis, knows medicine." Initial diagnosis is usually made on serum and cerebrospinal fluid examination. Penicillin is an effective treatment for neurosyphilis to stop progression of neurologic damage, but it does not cure the previously developed tabetic arthropathy. This case is reported to raise awareness of this uncommon but important manifestation of tertiary syphilis. Unfamiliarity with the clinical presentation of tabetic arthropathy may lead to considerable delay in diagnosis.

REVIEW: Neurosyphilis: A historical perspective and review

Treponema pallidum subspecies pallidum, the causative agent of syphilis, disseminates to the central nervous system within days after exposure. Clinical manifestations can occur during any stage of the infection, and include asymptomatic neurosyphilis, acute meningeal syphilis, meningovascular syphilis, paretic neurosyphilis, and tabetic neurosyphilis. The majority of cases are reported in HIV-infected patients but the epidemiology of modern neurosyphilis is not well defined because of the paucity of population-based data. Decreasing reports of late neurosyphilis have been countered with increasing reports of early neurologic involvement. This review summarizes the clinical manifestations, diagnosis, and therapy of neurosyphilis, focusing on areas of continued controversy, and highlighting several important questions that remain unanswered. Since 2000, the rates of syphilis continue to increase. Given the effectiveness of penicillin therapy, these trends suggest a failure of prevention. Regrettably, rather than become an infection of historical significance, syphilis in the era of HIV continues to challenge researchers and clinicians.