Anolik Jennifer H, Barnard Jennifer, Cappione Amedeo, Pugh-Bernard Aimee E, Felgar Raymond E, Looney R John, Sanz Iñaki
University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA.
Arthritis Rheum. 2004 Nov;50(11):3580-90. doi: 10.1002/art.20592.
B lymphocyte depletion has recently emerged as a promising approach to the treatment of systemic lupus erythematosus (SLE). As part of a phase I/II dose-ranging trial of rituximab in the treatment of SLE, we evaluated the fate of discrete B cell subsets in the setting of selective depletion by anti-CD20 monoclonal antibody and during the B cell recovery phase.
B cell depletion and phenotype were examined by flow cytometry of peripheral blood mononuclear cells for CD19, CD20, CD27, IgD, and CD38 expression. Changes in autoreactive B lymphocytes and plasma cells were assessed by determination of serum autoantibody levels (anti-double-stranded DNA and VH4.34) and by direct monitoring of a unique autoreactive B cell population bearing surface antibodies whose heavy chain is encoded by the VH4.34 gene segment.
Compared with normal controls, SLE patients displayed several abnormalities in peripheral B cell homeostasis at baseline, including naive lymphopenia, expansion of a CD27-,IgD- (double negative) population, and expansion of circulating plasmablasts. Remarkably, these abnormalities resolved after effective B cell depletion with rituximab and immune reconstitution. The frequency of autoreactive VH4.34 memory B cells also decreased 1 year posttreatment, despite the presence of low levels of residual memory B cells at the point of maximal B cell depletion and persistently elevated serum autoantibody titers in most patients.
This study is the first to show evidence that in SLE, specific B cell depletion therapy with rituximab dramatically improves abnormalities in B cell homeostasis and tolerance that are characteristic of this disease. The persistence of elevated autoantibody titers may reflect the presence of low levels of residual autoreactive memory B cells and/or long-lived autoreactive plasma cells.
B淋巴细胞清除疗法最近已成为治疗系统性红斑狼疮（SLE）的一种有前景的方法。作为利妥昔单抗治疗SLE的I/II期剂量范围试验的一部分，我们评估了在抗CD20单克隆抗体选择性清除以及B细胞恢复阶段离散B细胞亚群的命运。
通过对外周血单个核细胞进行流式细胞术检测CD19、CD20、CD27、IgD和CD38表达，以检查B细胞清除和表型。通过测定血清自身抗体水平（抗双链DNA和VH4.34）以及直接监测携带表面抗体且重链由VH4.34基因片段编码的独特自身反应性B细胞群体，评估自身反应性B淋巴细胞和浆细胞的变化。
与正常对照相比，SLE患者在基线时外周B细胞稳态存在多种异常，包括幼稚淋巴细胞减少、CD27 - 、IgD - （双阴性）群体扩增以及循环浆母细胞扩增。值得注意的是，使用利妥昔单抗有效清除B细胞并进行免疫重建后，这些异常得以解决。尽管在最大程度B细胞清除时存在低水平的残留记忆B细胞，且大多数患者血清自身抗体滴度持续升高，但治疗1年后自身反应性VH4.34记忆B细胞的频率也有所下降。
本研究首次表明，在SLE中，利妥昔单抗特异性B细胞清除疗法可显著改善该疾病特有的B细胞稳态和耐受性异常。自身抗体滴度持续升高可能反映了低水平残留自身反应性记忆B细胞和/或长寿自身反应性浆细胞的存在。
