Background/Purpose: Microtubule associated protein-2 (MAP-2) is found exclusively in nerve cells. MAP-2 has been shown to stabilize microtubules by binding to the outer surface and participate in determining the structure of nerve cells. Interestingly, a previous report has shown that an autoantibody against MAP-2 has been reported to be found in sera with SLE patients especially having neuropsychiatric manifestations. However, there are no additional reports concerning anti-MAP-2 antibody. NPSLE involves a wide range of focal and diffuse central and peripheral nervous system disorders. The diagnosis of NPSLE is often clinically difficult because discrimination of secondary causes such as infection, medication side-effects, and metabolic abnormalities was required. The diagnostic inference of NPSLE can be made only after these secondary causes have been excluded. There is no one single diagnostic tool specific to NPSLE so far. Multiple diagnostic examinations such as IL-6 measurement in cerebrospinal fluid or Magnetic Resonance Imaging (MRI) have been used for diagnosis with NPSLE. However, the findings from these examinations are not specific for NPSLE. Therefore, novel diagnostic biomarkers have been expected to be established. Herein, we conducted this study to clarify that anti-MAP-2 antibody in cerebrospinal fluid can be used for a diagnostic biomarker of NPSLE.

Methods: Anti-MAP-2 antibody, anti-ribosomal P antibody, and IL-6 was measured by ELISA in cerebrospinal fluid from NPSLE patients (n=24) or non NPSLE controls (n=18). The diagnosis with NPSLE was made by the nomenclature system proposed by American College of Rheumatology (ACR, 1999). Non NPSLE controls consisted of SLE patients with CNS disorders caused by the secondary causes such as steroid psychosis, and other tissue connective diseases with CNS disorder.

Results: Titer of anti-MAP-2 antibody in cerebrospinal fluid was significantly higher in NPSLE patients compared to non NPSLE controls. When the cutoff value was designed as average + 3SD of the controls, the prevalence of anti-MAP-2 antibody in NPSLE patients was 33.3% (8/24), and none of patients with non NPSLE controls (0/18) had an anti-MAP-2 antibody. Furthermore, titer of anti-ribosomal P antibody and IL-6 concentration in cerebrospinal fluid, which are other diagnostic biomarker for NPSLE, were significantly higher in NPSLE patients with anti-MAP-2 antibody compared to NPSLE patients without anti MAP-2 antibody or non NPSLE controls.

Conclusion: Anti-MAP-2 antibody in cerebrospinal fluid was recognized in 33.3% patients with NPSLE and the appearance was highly specific for NPSLE. We propose that anti-MAP-2 antibody in cerebrospinal fluid is a novel diagnostic biomarker for NPSLE.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/usefulness-of-diagnostic-biomarker-for-neuropsychiatric-systemic-lupus-erythematosus-by-anti-microtubule-associated-protein-2-antibody-in-cerebrospinal-fluid/