Abstract Details

Title H-Intensity Scale (HIS) Score for Estimation of CSF GluN1 Antibody Titers with One-Time Immunostaining using a Commercial Assay

Topic Autoimmune Neurology

Presentation(s) P5 - Poster Session 5 (5:30 PM-6:30 PM)

Poster/Presentation
Number 14-002

Objective

We aimed to develop H-Intensity Scale [HIS] score to estimate GluN1-antibody (ab) titers in CSF with one-time immunostaining using both commercial CBA and immunohistochemistry. The “H” is the initial of a patient with high CSF titers (1:2048).

Background Anti-NMDA receptor encephalitis is an autoimmune disorder caused by GluN1-abs. GluN1-abs have been determined with live or fixed CBA co-expressing GluN1/GluN2 subunits. However, in clinical practice, commercial fixed CBA expressing only GluN1 subunits has increasingly been used. Ab titers are usually determined with serial dilutions but its clinical significance remains unclear.

Design/Methods Of 710 patients tested for neuronal surface abs at Dalmau’s Lab., 368 tested with commercial CBA were included in Part I to determine its reliability. In Part II, the patient H’s CSF was diluted in a 4-fold serial dilution method (1:2, 1:8, 1:32, 1:128, 1:512, and 1:2048) to make positive control panels. Based on the panels, we scored the intensity of ab reactivity of 79 GluN1-ab-positive patients' CSF (diluted 1:2) on a scale from 0-6 (with >1 considered positive). Clinical significance of the scores of pre-treatment CSF obtained ≤ 4 weeks of encephalitis symptom onset was investigated.

Results Sensitivity and specificity of the commercial CBA was 93.7% (95% CI 85.8-97.9) and 98.6% (95% CI 96.5-99.6), respectively. Patients with typical phenotype, high NEOS score, dyskinesias, decreased level of consciousness, autonomic symptoms/hypoventilation, mechanical ventilation support, speech dysfunction, prodromal headache, or oligoclonal bands had higher median HIS score than those without, but there was no difference between patients with and without psychobehavioral alterations, seizures, tumor, or poor one-year functional status.

Conclusions HIS score that enables to estimate CSF titers provides important information in predicting subsequent course of the disease. High CSF titers that reflect a disease activity may not play an important role on one-year functional status. Incomplete phenotype can be attributed to low CSF titers.

Authors/Disclosures
Takahiro Iizuka, MD (Department of Neurology, Kitasato University School of Medicine) PRESENTER	The institution of Dr. Iizuka has received research support from EUROIMMUN Japan Co., Ltd.
Masaki Iizuka (Kitasato University School of Medicine)	Masaki Iizuka has nothing to disclose.
Naomi Nagata	Naomi Nagata has nothing to disclose.
Naomi Kanazawa	Naomi Kanazawa has nothing to disclose.
Tomomi Iwami (Kitasato University, School of Medicine)	Tomomi Iwami has nothing to disclose.
Makoto Nagashima	No disclosure on file
Masaaki Nakamura	Masaaki Nakamura has nothing to disclose.
Juntaro Kaneko	Juntaro Kaneko has nothing to disclose.
Eiji Kitamura	Eiji Kitamura has nothing to disclose.
Kazutoshi Nishiyama, MD, PhD	Kazutoshi Nishiyama, MD, PhD has nothing to disclose.

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