高濃度抗IgE自己抗体と高IgE血症を認め，アトピー性疾患に併発した抗アクアポリン4抗体陰性視神経脊髄炎スペクトラム障害の1例

A Case of the Anti-aquaporine-4 Antibody-negative Neuromyelitis Optica Spectrum Disorders Associated with Atopic Disease with High Concentration of Anti-IgE Autoantibody and HyperIgEemia

70歳，男性。20歳時にアレルギー性鼻炎と診断され，61歳時に抗アクアポリン4抗体（anti-aquaporine-4 antibody：抗AQP4抗体）陰性視神経脊髄炎スペクトラム障害（neuromyelitis optica spectrum disorders：NMOSD）を発症した。高IgE（immunoglobulin E）血症，高濃度抗IgE自己抗体（anti-IgE autoantibody：抗IgE AAb），抗原特異的IgE陽性およびヘルパーT細胞I型優位性を示し，脊髄MRIで第1頸髄〜脊髄円錐に及ぶ長大横断性脊髄炎（longitudinally extensive transvers myelitis：LETM）を認めた。発症時にはステロイドパルス療法（intravenous methylprednisolone：IVMP）と単純血漿交換（plasma exchange：PE）により，4回の再発時にはIVMPにより，神経症状と脊髄MRI所見の部分改善および抗IgE AAb低下を認めた。抗IgE AAbはアトピー性疾患に併発する抗AQP4抗体陰性NMOSDにおいて，疾患活動性の指標になり得ると考えられる。

Abstract

We report a 70-year-old male patient with the sero-negative neuromyelitis optica spectrum disorders (NMOSD) associated with atopic disease (AD). He was diagnosed with allergic rhinitis at the age of 20. When he was 61 years old, he subacutely developed orthostatic hypotension, bilateral optic neuritis, quadriparesis, urinary retention, and constipation. The laboratory results revealed allergen-specific IgE positivity for cryptomeria japonica and hinoki, hyperIgEemia, and Th (helper T cell) 1 dominance. The serological tests for autoantibodies revealed negative anti-aquaporine 4 antibody, and high concentration of anti-IgE autoantibody (anti-IgE AAb). Cerebrospinal fluid was negative for anti-myelin-oligodendrocyte glycoprotein antibody and glial fibrillary acidic protein antibody. Fluid-attenuated inversion recovery on brain magnetic resonance imaging (MRI) showed high signal intensities in bilateral cerebral deep white matter. T2 weighted image on spine MRI showed longitudinally extensive high signal intensities in the spinal cord, specifically involving C1 vertebral level to conus medullaris. Intravenous methylprednisolone (IVMP) and plasma exchange resulted in partial improvement. Following the onset of NMOSD, he had relapse of NMOSD four times. In each episode, IVMP was to be partially effective with anti-IgE AAb reduction. Anti-IgE AAb may be a reasonable clinical indicator of increased disease activity in the sero-negative NMOSD associated with AD.