Blood group systems biosynthesis

The association between blood type and disease has been studied since the beginning of the 20th Century (Anstee 2010, Ewald & Sumner 2016). Landsteiner's discovery of blood groups in 1900 was based on agglutination patterns of red blood cells when blood types from different donors were mixed (Landsteiner 1931, Owen 2000, Tan & Graham 2013). His work is the basis of routine compatibility testing and transfusion practices today. The immune system of patients receiving blood transfusions will attack any donor red blood cells that contain antigens that differ from their self-antigens. Therefore, matching blood types is essential for safe blood transfusions. Landsteiner's classification of the ABO blood groups confirmed that antigens were inherited characteristics. In the 1940s, it was established that the specificity of blood group antigens was determined by their unique oligosaccharide structures. Since then, exponential advances in technology have resulted in the identification of over 300 blood group antigens, classified into more than 35 blood group systems by the International Society of Blood Transfusion (ISBT) (Storry et al. 2016).<br><br>Blood group antigens comprise either a protein portion or oligosaccharide sequence attached on a glycolipid or glycoprotein. The addition of one or more specific sugar molecules to this oligosaccharide sequence at specific positions by a variety of glycosyltransferases results in the formation of mature blood group antigens. The genes that code for glycosytransferases can contain genetic changes that produce antigenic differences, resulting in new antigens or loss of expression. Blood group antigens are found on red blood cells (RBCs), platelets, leukocytes, and plasma proteins and also exist in soluble form in bodily secretions such as breast milk, seminal fluid, saliva, sweat, gastric secretions and urine. Blood groups are implicated in many diseases such as those related to malignancy (Rummel & Ellsworth 2016), the cardiovascular system (Liumbruno & Franchini 2013), metabolism (Meo et al. 2016, Ewald & Sumner 2016) and infection (Rios & Bianco 2000, McCullough 2014). The most important and best-studied blood groups are the ABO, Lewis and Rhesus systems. The biosynthesis of the antigens in these systems is described in this section.

血型与疾病之间的关联研究始于20世纪初（Anstee 2010，Ewald & Sumner 2016）。1900年，兰德斯坦纳（Landsteiner）基于不同供血者血型混合后红细胞凝集模式发现了血型（Landsteiner 1931，Owen 2000，Tan & Graham 2013）。其研究奠定了当今常规配型试验和输血实践的基础。接受输血的患者免疫系统将攻击含有与自身抗原不同的抗原的任何供血者红细胞。因此，匹配血型对于安全的输血至关重要。兰德斯坦纳对ABO血型的分类证实了抗原是遗传特征。20世纪40年代，确立了血型抗原的特异性由其独特的寡糖结构决定。自那时起，技术的指数级进步导致了超过300种血型抗原的鉴定，这些抗原被国际输血协会（ISBT）划分为超过35个血型系统（Storry et al. 2016）。

血型抗原由附着在糖脂或糖蛋白上的蛋白质部分或寡糖序列组成。通过多种糖基转移酶在寡糖序列的特定位置添加一个或多个特定糖分子，形成成熟的血型抗原。编码糖基转移酶的基因可能包含产生抗原性差异的遗传变化，导致新抗原的产生或表达丧失。血型抗原存在于红细胞（RBCs）、血小板、白细胞和血浆蛋白上，并在体液分泌中存在可溶性形式，如母乳、精液、唾液、汗液、胃液和尿液。血型与许多疾病有关，如与恶性肿瘤（Rummel & Ellsworth 2016）相关疾病、心血管系统（Liumbruno & Franchini 2013）、代谢（Meo et al. 2016，Ewald & Sumner 2016）和感染（Rios & Bianco 2000，McCullough 2014）。其中，最重要的、研究最深入的血型系统是ABO、利文斯和Rh系统。本节描述了这些系统中抗原的生物合成。