背景:免疫系统能够识别源自体内或体外并具有潜在危害的物质。与免疫系统组分结合的外来物质表现出抗原性并被定义为抗原。显示免疫原性的抗原可诱导先天或适应性免疫应答,并产生体液或细胞介导的免疫。显示有丝分裂原活性的抗原可交联B和T淋巴细胞上的细胞膜受体,导致细胞增殖。所有的抗原在物理化学特征如生化性质有很大差异,结构复杂性,分子大小,外国人,溶解度,等等。
目标:因此,这篇综述旨在描述蛋白质抗原性的分子基础和导致免疫反应的分子基础,淋巴细胞增殖,或反应迟钝。
结论:抗原的表位位于表面区域;它们的大小为约880-3,300Da。它们是蛋白质,碳水化合物,或脂质性质。可溶性抗原小于1nm并且内吞效率低于颗粒抗原。抗原的结构复杂性增加得越多,由于表位的数量和多样性,抗原性增加得越多。最小的免疫原大小约为4,000-10,000Da。来自免疫原受体的系统发育距离越远,免疫原性越强。作为免疫原的抗原可以触发先天或适应性免疫应答。先天反应是由病原体相关分子模式的抗原诱导的。外源性抗原,T依赖或T独立,诱导体液免疫原性。TD蛋白抗原需要两个表位,一种顺序和一种构象诱导抗体,然而,TI非蛋白质抗原仅需要一个构象表位来诱导低亲和力抗体。内源性蛋白质抗原仅需要一个顺序表位来诱导细胞介导的免疫原性。
BACKGROUND: The immune system is able to recognize substances that originate from inside or outside the body and are potentially harmful. Foreign substances that bind to immune system components exhibit antigenicity and are defined as antigens. The antigens exhibiting immunogenicity can induce innate or adaptive immune responses and give rise to humoral or cell-mediated immunity. The antigens exhibiting mitogenicity can cross-link cell membrane receptors on B and T lymphocytes leading to cell proliferation. All antigens vary greatly in physicochemical features such as biochemical nature, structural complexity, molecular size, foreignness, solubility, and so on.
OBJECTIVE: Thus, this review aims to describe the molecular bases of protein-antigenicity and those molecular bases that lead to an immune response, lymphocyte proliferation, or unresponsiveness.
CONCLUSIONS: The epitopes of an antigen are located in surface areas; they are about 880-3,300 Da in size. They are protein, carbohydrate, or lipid in nature. Soluble antigens are smaller than 1 nm and are endocytosed less efficiently than particulate antigens. The more the structural complexity of an antigen increases, the more the antigenicity increases due to the number and variety of epitopes. The smallest immunogens are about 4,000-10,000 Da in size. The more phylogenetically distant immunogens are from the
immunogen-recipient, the more immunogenicity increases. Antigens that are immunogens can trigger an innate or adaptive immune response. The innate response is induced by antigens that are pathogen-associated molecular patterns. Exogenous antigens, T Dependent or T Independent, induce humoral immunogenicity. TD protein-antigens require two epitopes, one sequential and one conformational to induce antibodies, whereas, TI non-protein-antigens require only one conformational epitope to induce low-affinity antibodies. Endogenous protein antigens require only one sequential epitope to induce cell-mediated immunogenicity.