MOLECULAR GENETICS OF COMPLEMENT C4

人类HLA复合体的标志是多态性（i）。就像I类， II基因座是补体基因座的III类第四组分，即C4 A和 C4 B是高度多态的，具有超过35个等位基因。遗传研究 已经绘制了多种疾病的易感性，特别是免疫性疾病 复杂（ic）疾病，该区域的HLA。长期目标 这一建议的目的是了解基因的功能重要性， 多态性及其与免疫反应的关系， 疾病易感性这一目标分为三个部分 具体目标：（1）确定结构基础和功能 C4多态性的意义;（2）确定遗传因素对C4多态性的影响。 C4同种型对人类免疫应答的变化;（3）开发 用于分析C4蛋白在免疫中的作用的遗传模型 体内反应。 第一个目的是检验这一假设，即同种型和 同种异型残基影响与IC的共价结合。人C4 A和C4 B 使用定点诱变使编码序列突变。 了解这些残基对结合的影响很重要，因为 结合的效率直接决定了 道路。 本建议的第二个目的是检验非- 对B肝炎疫苗的应答是由于纯合的C4 A无效等位基因。 这将通过将先前的研究扩展到包括个人来进行测试 C4 A无效等位基因纯合，但HLA单倍型其他 B8 DR3 C4同种型影响免疫反应的发现 某些疫苗将是非常重要的。 第三个目标提出开发C4缺陷小鼠品系。这 菌株将用于本建议：（1）表征的作用 补体在免疫反应中的作用;（2）遗传操作， 插入人C4 A或C4 B的转基因;（3）直接比较 C4 A和C4 B转基因小鼠的免疫应答;以及（4）发展中国家的 一种人类替代疗法的策略。 综上所述，（1）生物化学研究的组合方法 C4结构变异的重要性;（2）人类疫苗接种 具有两种不同抗原的C4 A或C4 B无效等位基因纯合子; （3）构建C4缺陷型和C4 A/C4 B转基因小鼠， 关于C4在免疫应答中的作用以及 多态性对其作用的影响;将回答重要的问题， 将引领人类疾病的未来治疗。

A hallmark of the HLA complex in man is polymorphism (i). Like class I and II loci the class III fourth component of complement loci, i.e. C4A and C4B, are highly polymorphic with more than 35 alleles. Genetic studies have mapped susceptibility to a number of diseases, in particular immune complex (ic) disease, to this region of the HLA. The long term objective of this proposal is to understand the functional importance of the genetic polymorphism and how it might be related to the immune response and disease susceptibility. This objective has been organized into three specific aims: (1) Determine the structural basis and functional significance of C4 polymorphism; (2) Determine the affect of genetic variation of the C4 isotypes on the human immune response; (3) Develop genetic models for the analysis of the role of C4 protein in the immune response in vivo. The first aim proposes to test the hypothesis that both the isotypic and allotypic residues affect covalent binding to the ic. Human C4A and C4B coding sequences will be mutated using site-directed mutagenesis. Understanding the affect these residues have on binding is important since the efficiency of binding directly determines the extent of activation of the pathway. The second aim of this proposal is to test the hypothesis that non- response to hepatitis B vaccine is due to homozygous C4A null alleles. This will be tested by extending the previous study to include individuals that are homozygous for the C4A null allele but on HLA haplotypes other than B8 DR3. The finding that C4 isotype affects the immune response to certain vaccines would be of significant importance. The third aim proposes to develop a C4 deficient strain of mouse. This strain will be used in this proposal for: (1) characterization of the role of complement in the immune response; (2) genetic manipulation such as insertion of transgenes of either human C4A or C4B; (3) direct comparison of the immune response by C4A and C4B transgenic mice; and (4) developing a strategy for a replacement therapy in humans. In summary, the combined approach of (1) biochemical studies on the importance of the structural variation of C4; (2) vaccination of humans homozygous for either C4A or C4B null alleles with two different antigens; and (3) construction of C4 deficient and C4A/C4B transgenic mice for biological studies on both the role of C4 in the immune response and the affect of polymorphism on its role; will answer important questions that will lead to future therapy against human disease.