From the Neuroimmunology and Multiple Sclerosis Unit of the Neurology Division (A.W.-Y., A.K.), Tel Aviv Sourasky Medical Center; Clinical Immunology Laboratory (Y.A.), Tel Aviv Sourasky Medical Center; Laboratory of Neuroimmunology (T.B.), Department of Neurology, the Agnes Ginges Center for Human Neurogenetics, Hadassah-Hebrew University Medical Center, Jerusalem; Sackler Faculty of Medicine (A.K.), Tel Aviv University; and Sagol School of Neuroscience (A.K.), Tel Aviv University, Israel.
Neurol Neuroimmunol Neuroinflamm. 2020 Jul 14;7(5). doi: 10.1212/NXI.0000000000000831. Print 2020 Sep.
To investigate the hypothesis that free light chain (FLC) sera levels could serve as a biomarker for myasthenia gravis (MG), especially for the subgroups of seronegative MG and ocular MG.
Sera from 73 patients with MG (20 seronegative for antiacetylcholine receptor [AChR] and anti-muscle-specific kinase and 53 positive for anti-AChR, which were clinically divided into 24 patients with ocular type, 45 with generalized type, and 4 with unequivocal clinical manifestation) and 49 healthy controls were studied for κ FLC and λ FLC levels with the Freelite human FLC kits.
The κ but not the λ levels of FLC were significantly increased in the patients with MG, including those with double seronegative MG and ocular MG, compared with the healthy controls. The specificity for double seronegative MG and ocular MG were both 98.0% when κ FLC was ≥25.0 mg/L. Increased κ FLC levels were not affected by the patient's sex, age at MG onset, the presence of thymic pathology, or different treatments.
Elevated serum κ FLC may serve as a biomarker for MG in suspected patients who are double seronegative and in those with only ocular manifestations when serology is inconclusive.
This study provides Class III evidence that high κ FLC levels distinguished patients with MG, including those who were double seronegative, from healthy controls.
探讨血清游离轻链（FLC）水平是否可作为重症肌无力（MG）的生物标志物，尤其是对血清阴性 MG 和眼肌型 MG 亚组的作用。
采用 Freelite 人 FLC 试剂盒检测 73 例 MG 患者（20 例抗乙酰胆碱受体 [AChR]和抗肌肉特异性激酶抗体阴性，53 例抗 AChR 抗体阳性，临床分为眼肌型 24 例、全身型 45 例和明确临床表现型 4 例）和 49 例健康对照者的κ FLC 和 λ FLC 水平。
与健康对照组相比，MG 患者，包括双阴性 MG 和眼肌型 MG 患者，κ FLC 而非 λ FLC 水平显著升高。κ FLC≥25.0mg/L 时，对双阴性 MG 和眼肌型 MG 的特异性均为 98.0%。κ FLC 水平升高不受患者性别、MG 发病年龄、胸腺瘤病理存在与否以及不同治疗的影响。
血清中κ FLC 的升高可能有助于诊断血清学检查不确定的双阴性和仅有眼部表现的可疑 MG 患者。
本研究提供了 III 级证据，表明高 κ FLC 水平可区分 MG 患者，包括双阴性患者，与健康对照者。
