Glycosylation of autoantibodies: Insights into the mechanisms of immune thrombocytopenia
Glycosylation of autoantibodies: Insights into the mechanisms of immune thrombocytopenia
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DOI：
10.1160/th13-04-0294
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发表时间：
2013-12-01
影响因子：
6.7
通讯作者：
Sachs, Ulrich J.
中科院分区：
文献类型：
--
作者：
Bakchoul, Tamam;Walek, Kathrin;Sachs, Ulrich J.
免疫性血小板减少症（ITP）是由针对血小板（PLT）的IgG自身抗体（AAbs）引起的出血性疾病。IgG效应子功能取决于其Fc恒定区，其经历翻译后糖基化。我们在体外和体内研究了Asn 279连接的AAbs N-聚糖的作用。从ITP患者（n=15）中纯化AAbs，并通过内切糖苷酶F酶切N-聚糖。应用流式细胞术、激光扫描显微镜和补体消耗测定法，在体外比较天然AAbs和去糖基化AAbs对单核细胞吞噬血小板和补体固定和活化的增强作用。AAb诱导的血小板吞噬作用受到N-聚糖裂解的抑制（中位吞噬活性：8% vs 0.8%，p=0.004）。15个天然AAb中有7个结合C1 q并激活补体。N-聚糖裂解显著降低了这两种效应。在NOD/SCID小鼠模型中，在与天然或N-聚糖切割的AAb共输注后评估人PLT的体内存活。与对照组相比，注射AAbs导致人血小板的快速清除（5 h后血小板清除率（CL 5 h）为75% vs 30%，p
Immune thrombocytopenia (ITP) is a bleeding disorder caused by IgG autoantibodies (AAbs) directed against platelets (PLTs). IgG effector, functions depend on their Fc-constant region which undergoes post; translational glycosylation. We investigated the role of Asn279-linked N-glycan of AAbs in vitro and in vivo. AAbs were purified from ITP patients (n=15) and N-glycans were enzymatically cleaved by endoglycosidase F. The effects of native AAbs and deglycosylated AAbs were compared in vitro on enhancement of phagocytosis of platelets by monocytes and complement fixation and activation applying flow cytometry, laser scanning microscopy, and a complement consumption assay. AAb-induced platelet phagocytosis was inhibited by N-glycan cleavage (median phagocytic activity: 8% vs 0.8%, p=0.004). Seven out of 15 native AAbs bound C1q and activated complement. N-glycan cleavage significantly reduced both effects. In vivo survival of human PLTs was assessed after co-transfusion with native or N-glycan cleaved AAbs in a NOD/SCID mouse model. Injection of AAbs resulted in rapid clearance of human platelets compared to control (platelet clearance after 5h (CL5h) 75% vs 30%, p