B-cell activating factor (BAFF), a member of tumor necrosis factor family, activates B cells, promotes their survival and proliferation. BAFF is considered to have an influence on development of autoimmune diseases including myasthenia gravis (MG). We aimed to evaluate BAFF serum levels in MG patients, their potential connection with therapy and course of MG. Cross-sectional study. Two hundred eighteen adult patients with MG (67% women, age: 18–89 years, 82.6% AChR antibody seropositive (AChRAb(+)). Serum BAFF levels, their relationship with severity of clinical symptoms, therapy conducted, clinical and demographic features and other factors were analyzed. Patients with AChRAb(+) MG demonstrated significantly higher BAFF levels than MuSK-MG patients (831.2 ± 285.4 pg/ml vs. 745.6 ± 633.4 pg/ml, respectively; p = 0.030). Serum BAFF levels in women were significantly higher than in men (855.9 ± 302.5 vs. 756.6 ± 289.4, respectively; p = 0.017). Mean serum BAFF level was significantly decreased in patients who were ever treated with corticosteroids (CS) (770.4 ± 327.8 pg/ml vs. 891.3 ± 246.1 pg/ml, respectively; p = 0.001). Thymoma-MG patients demonstrated significantly lower BAFF levels (671.2 ± 244.9 vs. 833.5 ± 302.4, respectively; p = 0.044). Thymectomized patients did not differ in BAFF levels from the MG patients who had not undergone thymectomy. In multiple linear regression model, recent CS therapy and male sex were found to be independent predictors of lower BAFF levels. Serum BAFF level is decreased in patients treated with CS, which may suggest inhibiting influence of CS on BAFF—a potential mechanism contributing to the effectiveness of such therapy.

B细胞激活因子（BAFF）是肿瘤坏死因子家族的成员，可激活B细胞，促进其存活和增殖。BAFF 被认为对包括重症肌无力 (MG) 在内的自身免疫性疾病的发展有影响。我们旨在评估 MG 患者的 BAFF 血清水平，它们与治疗和 MG 病程的潜在联系。横断面研究。218 名成人 MG 患者（67% 的女性，年龄：18-89 岁，82.6% 的 AChR 抗体血清阳性 (AChRAb(+))。血清 BAFF 水平，它们与临床症状严重程度的关系、所进行的治疗、临床和人口统计学特征AChRAb(+) MG 患者的 BAFF 水平显着高于 MuSK-MG 患者（分别为 831.2 ± 285.4 pg/ml 和 745.6 ± 633.4 pg/ml；p = 0.030)。女性的血清 BAFF 水平显着高于男性（分别为 855.9 ± 302.5 和 756.6 ± 289.4；p  = 0.017）。曾接受皮质类固醇 (CS) 治疗的患者的平均血清 BAFF 水平显着降低（分别为 770.4 ± 327.8 pg/ml 和 891.3 ± 246.1 pg/ml；p  = 0.001）。胸腺瘤-MG 患者的 BAFF 水平显着降低（分别为 671.2 ± 244.9 和 833.5 ± 302.4；p = 0.044)。胸腺切除术患者的 BAFF 水平与未接受胸腺切除术的 MG 患者没有差异。在多元线性回归模型中，发现最近的 CS 治疗和男性是较低 BAFF 水平的独立预测因子。接受 CS 治疗的患者血清 BAFF 水平降低，这可能表明 CS 对 BAFF 的影响具有抑制作用——这是一种有助于此类治疗有效性的潜在机制。