Palmetshofer A, Galili U, Dalmasso A P, Robson S C, Bach F H
Novartis Center for Immunobiology, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
Transplantation. 1998 Mar 27;65(6):844-53. doi: 10.1097/00007890-199803270-00013.
The galactose alpha(1-3)galactose (alpha-gal) epitope associated with membrane glycoproteins and glycolipids represents a major determinant recognized on porcine cells by human xenoreactive natural antibodies (XNA). Together, bound XNA and complement rapidly induce porcine aortic endothelial cell (PAEC) activation; this process is associated with cellular shape changes, transient development of intercellular gaps, and loss of ATDPase and thrombomodulin, with release of heparan sulfate. The aim of this study was to evaluate patterns of type I endothelial cell activation (i.e., activation that does not require protein synthesis) following ligation of alpha-gal epitopes with anti-Gal antibodies and alpha-gal-specific lectins.
PAEC incubated in the presence of the alpha-gal binding, Bandeiraea simplicifolia lectin (BS-I) underwent cellular shape changes associated with the formation of intercellular gaps. PAEC exposure to BS-I was also associated with the tyrosine phosphorylation of a protein (apparent molecular mass of approximately 130 kDa), not observed following lipopolysaccharide, tumor necrosis factor, or XNA stimulation. This lectin-induced tyrosine phosphorylation was not affected by cytochalasin D (inhibitor of actin filament polymerization), by genistein (inhibitor of tyrosine kinases), or by staurosporine (inhibitor of tyrosine phosphorylation and protein kinase C). In addition, incubation of PAEC with BS-I and monoclonal anti-Gal IgM induced p42/44 map kinase and activated the transcription factor NF-kappaB.
Agonist binding of alpha-gal can evoke endothelial cell activation independently of complement activation. These observations have implications for the survival of xenografts.
与膜糖蛋白和糖脂相关的半乳糖α(1-3)半乳糖（α-半乳糖）表位是人类异种反应性天然抗体（XNA）识别猪细胞的主要决定因素。结合的XNA和补体共同作用可迅速诱导猪主动脉内皮细胞（PAEC）活化；这一过程与细胞形态改变、细胞间隙的短暂形成以及ADP酶和血栓调节蛋白的丧失有关，并伴有硫酸乙酰肝素的释放。本研究的目的是评估用抗Gal抗体和α-半乳糖特异性凝集素连接α-半乳糖表位后I型内皮细胞活化（即不需要蛋白质合成的活化）的模式。
在α-半乳糖结合的单叶豆凝集素（BS-I）存在下孵育的PAEC发生了与细胞间隙形成相关的细胞形态改变。PAEC暴露于BS-I还与一种蛋白质（表观分子量约为130 kDa）的酪氨酸磷酸化有关，而在脂多糖、肿瘤坏死因子或XNA刺激后未观察到这种情况。这种凝集素诱导的酪氨酸磷酸化不受细胞松弛素D（肌动蛋白丝聚合抑制剂）、染料木黄酮（酪氨酸激酶抑制剂）或星形孢菌素（酪氨酸磷酸化和蛋白激酶C抑制剂）的影响。此外，用BS-I和单克隆抗Gal IgM孵育PAEC可诱导p42/44丝裂原活化蛋白激酶并激活转录因子NF-κB。
α-半乳糖的激动剂结合可独立于补体激活引发内皮细胞活化。这些观察结果对异种移植物的存活具有重要意义。
