In the last few years, anti-CD20 antibody rituximab profoundly changed the therapeutic landscape of granulomatosis with polyangiitis (GPA). Here, we investigated whether natural killer (NK) cells may play a role in rituximab’s mechanism of action in GPA. B cell depletion, NK cell degranulation, and the expression of CD69 and CD16 on NK cells were measured in a series of in vitro experiments using peripheral blood mononuclear cells (PBMCs). In vivo activation of NK cells was investigated in patients receiving rituximab infusions. Cells were analyzed by seven-color flow cytometry. NK cells from GPA patients were activated by immobilized rituximab. Also soluble rituximab activated NK cells, provided that B cells were present. NK cells degranulated and expressed the activation marker CD69 while CD16 expression was decreased. This activation of NK cells by soluble rituximab was accompanied by a reduction of B cells. The next-generation anti-CD20 antibody obinutuzumab showed stronger effects compared to rituximab on both the reduction of B cells and the activation of NK cells. Finally, we found that rituximab led to the activation of NK cells in vivo, provided that B cells were not depleted due to prior rituximab infusions. B cell-bound rituximab activates NK cells in GPA. While NK cells therefore participate in rituximab’s mechanism of action in humans, their potential may be more efficiently exploited, e.g., by Fc engineering of therapeutic antibodies.

中文翻译：

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利妥昔单抗在肉芽肿合并多血管炎中激活自然杀伤细胞。

在最近几年中，抗CD20抗体利妥昔单抗深刻改变了肉芽肿合并多血管炎（GPA）的治疗前景。在这里，我们调查了自然杀伤（NK）细胞是否可能在GPA中利妥昔单抗的作用机制中起作用。使用外周血单核细胞（PBMC）在一系列体外实验中测量了B细胞耗竭，NK细胞脱粒以及NK细胞上CD69和CD16的表达。在接受利妥昔单抗输注的患者中研究了NK细胞的体内激活。通过七色流式细胞仪分析细胞。固定的利妥昔单抗可激活GPA患者的NK细胞。如果存在B细胞，也可溶解的利妥昔单抗激活的NK细胞。NK细胞脱粒并表达激活标记CD69，而CD16表达降低。可溶性利妥昔单抗对NK细胞的激活伴随着B细胞的减少。与利妥昔单抗相比，下一代抗CD20抗体obinutuzumab在减少B细胞和激活NK细胞方面均显示出比利妥昔单抗更强的作用。最后，我们发现利妥昔单抗可导致体内NK细胞的激活，前提是B细胞未因先前的利妥昔单抗输注而耗尽。B细胞结合的利妥昔单抗激活GPA中的NK细胞。因此，尽管NK细胞参与了利妥昔单抗在人体内的作用机制，但是它们的潜力可以被更有效地利用，例如通过治疗性抗体的Fc工程改造。与利妥昔单抗相比，下一代抗CD20抗体obinutuzumab在减少B细胞和激活NK细胞方面均显示出比利妥昔单抗更强的作用。最后，我们发现利妥昔单抗可导致体内NK细胞的激活，前提是B细胞未因先前的利妥昔单抗输注而耗尽。B细胞结合的利妥昔单抗激活GPA中的NK细胞。因此，尽管NK细胞参与了利妥昔单抗在人体内的作用机制，但是它们的潜力可以被更有效地利用，例如通过治疗性抗体的Fc工程改造。与利妥昔单抗相比，下一代抗CD20抗体obinutuzumab在B细胞减少和NK细胞活化方面均表现出更强的作用。最后，我们发现利妥昔单抗可导致体内NK细胞的激活，前提是B细胞未因先前的利妥昔单抗输注而耗尽。B细胞结合的利妥昔单抗激活GPA中的NK细胞。因此，尽管NK细胞参与了利妥昔单抗在人体内的作用机制，但是它们的潜力可以被更有效地利用，例如通过治疗性抗体的Fc工程改造。