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C5a是机体补体活化过程中产生的过敏毒素之一,某些疾病过程产生的非补体酶也可以裂解前体分子C5产生C5a。国外多家实验室已分离提纯了多种动物的C5aa 并进行了肽链初级和次级结构分析,证明C5a 分子存在受体识别位点和活化中心两个功能区。现已发现多种细胞具有C5a 受体,且受体—配基结合反应无种属特异性。C5a 在体内的生理作用包括致痉(平滑肌收缩和血管通透性增高)、粒细胞活化及调节机体免疫反应。其在临床损伤性疾病,特别是休克并发症中的作用已引起高度重视,目前已有采用抗C5a 抗体和抑制性药物治疗这些疾病的初步成果。
C5a is one of the anaphylatoxins that are produced during the body’s complement activation. Non-complement enzymes produced during certain disease processes can also cleave the precursor molecule C5 to C5a. A number of laboratories in foreign countries have isolated and purified C5aa of various animals and analyzed the primary and secondary structure of the peptide chain. It is proved that there are two functional domains of C5a molecule, ie receptor recognition site and activation center. A variety of cells have been found to have C5a receptors, and receptor-ligand binding reactions are not species-specific. The physiological role of C5a in the body includes spasm (smooth muscle contraction and increased vascular permeability), granulocyte activation, and the regulation of the immune response in the body. Its role in clinical injury, especially in shock complications has attracted great attention. At present, there are some preliminary results of using anti-C5a antibodies and suppressive drugs to treat these diseases.