An anti-C3b(i) mAb enhances complement activation, C3b(i) deposition, and killing of CD20+ cells by rituximab
An anti-C3b(i) mAb enhances complement activation, C3b(i) deposition, and killing of CD20+ cells by rituximab
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DOI：
10.1182/blood-2002-03-0876
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发表时间：
2003-02-01
期刊：
影响因子：
20.3
通讯作者：
Taylor, RP
中科院分区：
文献类型：
--
作者：
Kennedy, AD;Solga, MD;Taylor, RP
我们研究了补体蛋白片段C3 b及其分解产物（统称为C3 b（I））在正常人血清（NHS）存在下用利妥昔单抗（RTX）处理的CD 20阳性细胞上的沉积。放射免疫测定（RIA）显示每个细胞约有50万个C3 b（i）分子存款，荧光显微镜显示C3 b（l）与结合的RTX共定位。使用特异于与底物结合的C3 b（I）的mAb 3E 7增强C3 b（i）沉积;当细胞与NHS、RTX和mAb 3E 7孵育时，> 1百万C3 b（i）存款。拉吉的待遇！在NHS + RTX中的细胞在24至48小时后导致稳健的细胞杀伤（95%），并且mAb 3E 7显著增强RTX介导的Raji和DB细胞的杀伤。基于静脉输注RTX和mAb 3E 7的食蟹猴模型证明，RTX快速结合B细胞，并促进补体激活和C3 B（i）沉积;荧光显微镜分析显示，体内细胞结合RTX上C3 B（i）的共定位模式与体外观察到的相同。对慢性淋巴细胞白血病患者血液样本进行的初步体外研究得出了类似的结果。这些实验表明，补体在RTX的作用机制中起关键作用;此外，循环或组织中RTX（以及可能的其他抗肿瘤mAb）的体内分子形式可能包括与治疗性mAb共价结合的C3 b（i）分子，从而使其与含有Fc和补体受体的细胞相互作用。(C)2003年，美国血液学会。
We investigated deposition of the complement protein fragment C3b and its breakdown products (collectively designated as C3b(I)) on CD20-positive cells treated with rituximab (RTX) in the presence of normal human serum (NHS). Radioimmunoassay (RIA) demonstrates that about 500 000 C3b(i) molecules deposit per cell, and fluorescence microscopy reveals that C3b(l) colocalizes with bound RTX. Use of mAb 3E7, specific for C3b(I) bound to substrates, enhances C3b(i) deposition; > 1 million C3b(i) deposit when cells are incubated with NHS, RTX and mAb 3E7. Treatment of Raj! cells in NHS plus RTX leads to robust cell killing (95%) after 24 to 48 hours, and mAb 3E7 significantly enhances RTX-mediated killing of Raji and DB cells. A cynomolgus monkey model based on intravenous infusion of RTX followed by mAb 3E7 demonstrated that RTX rapidly binds to B cells and promotes complement activation and C3b(i) deposition; fluorescence microscopy analyses revealed the same pattern of colocalization of C3b(i) on cell-bound RTX in vivo as observed in vitro. Preliminary in vitro studies with blood samples from patients with chronic lymphocytic leukemia lead to similar findings. These experiments suggest that complement plays a key role in the mechanism of action of RTX; moreover, the in vivo molecular form of RTX (and possibly other antitumor mAbs) in the circulation or in tissues may include C3b(i) molecules covalently bound to the therapeutic mAb, thus allowing it to interact with cells containing both Fc and complement receptors. (C) 2003 by The American Society of Hematology.