抗体亲和力与亲合力的区别Affinity and Avidity of Antibodies

抗原抗体反应：是指抗原与相应抗体在体内或体外发生的特异性结合反应。

抗原抗体间的结合力涉及静电引力、范德华力、氢键和疏水作用力，其中疏水作用力最强，它是在水溶液中两个疏水基团相互接触，由于对水分子的排斥而趋向聚集的力。

亲和性（affinity）：是指抗体分子上一个抗原结合点与一个相应抗原表位（AD）之间的结合强度，取决于两者空间结构的互补程度。

亲合力（avidity）：是指一个完整抗体分子的抗原结合部位与若干相应抗原表位之间的结合强度，它与亲和性、抗体的结合价、抗原的有效AD数目有关。

抗原抗体反应的特点：特异性、可逆性、比例性、阶段性。

带现象（zone phenomenon）：一种抗原-抗体反应的现象。

在凝集反应或沉淀反应中，由于抗体过剩或抗原过剩，抗原与抗体结合但不能形成大的复合物，从而不出现肉眼可见的反应现象。

抗体过量称为前带，抗原过量称为后带。

免疫原（immunogen）：是指能诱导机体免疫系统产生特异性抗体或致敏淋巴细胞的抗原。

免疫佐剂（immuno adjustvant）：简称佐剂，是指某些预先或与抗原同时注入体内，可增强机体对该抗原的免疫应答或改变免疫应答类型的物质。

半抗原（hapten）：又称不完全抗原，是指仅具有与抗体结合的能力(抗原性)，而单独不能诱导抗体产生（无免疫原性）的物质。

当半抗原与蛋白质载体结合后即可成为完全抗原。

载体（carrier）：结合后能给予半抗原以免疫原性的物质。

载体效应：初次免疫与再次免疫时，只有使半抗原结合在同一载体上，才能使机体产生对半抗原的免疫应答，该现象称为~。

单克隆抗体（McAB）：将单个B细胞分离出来，加以增殖形成一个克隆群落，该B细胞克隆产生的针对单一表位、结构相同、功能均一的抗体，即~。

多克隆抗体（PcAb）：天然抗原分子中常含多种不同抗原特异性的抗原表位，以该抗原物质刺激机体免疫系统，体内多个B细胞克隆被激活，产生含有针对不同抗原表位的免疫球蛋白，即~基因工程抗体（GEAb）：是利用DNA重组及蛋白工程技术，从基因水平对编码抗体的基因进行改造和装配，经导入适当的受体细胞后重新表达的抗体。

Affinity and Avidity of AntibodiesAntibody AffinityAffinity measures the strength of interaction between an epitope and an antibody’s antigen binding site. It is defined by the same basic thermodynamic principles that govern any reversible biomolecular interaction:o K A= affinity constanto[Ab]= molar concentration of unoccupied binding sites on the antibodyo[Ag]= molar concentration of unoccupied binding sites on the antigeno[Ab-Ag]= molar concentration of the antibody-antigen complexIn other words, K A describes how much antibody-antigen complex exists at the point when equilibrium is reached. The time taken for this to occur depends on rate of diffusion and is similar for every antibody. However, high-affinity antibodies will bind a greater amount of antigen in a shorter period of time than low-affinity antibodies. K A can therefore vary widely for antibodies from below 105mol-1to above 1012mol-1, and can be influenced by factors including pH, temperature and buffer composition.The affinity of monoclonal antibodies can be measured accurately because they are homogeneous and selective for a single epitope. Polyclonal antibodies are heterogeneous and will contain a mixture of antibodies of different affinities recognizing several epitopes – therefore only an average affinity can be determined.Antibody AvidityAvidity gives a measure of the overall strength of an antibody-antigen complex. It is dependent on three major parameters:o Affinity of the antibody for the epitope (see above)o Valency of both the antibody and antigeno Structural arrangement of the parts that interactAll antibodies are multivalent e.g.IgGs are bivalent and and IgMs are decavalent. The greater an immunoglobulin’s valency (number of antigen binding sites), the greater the amount of antigen it can bind. Similarly, antigens can demonstrate multivalency because they can bind to more than one antibody. Multimeric interactions between an antibody and an antigen help their stabilization.A favorable structural arrangement of antibody and antigen can also lead to a more stable antibody-antigen complex as illustrated in Figures 1 and 2.Figure 1.An immobilized antigen (a high local concentration of available epitopes) provides more opportunity for the antibody-antigen complex to form than free antigen in solution over the same time period. Once the first antigen binding arm of an antibody attaches to an antigen on a solid support, the chances of a bivalent interaction are greatly improved. Many immunoassays like Western blotting and ELISA exploit this principle.Figure 2.When an antigen is mixed with a polyclonal antibody, multivalent interactions may lead to large, stable (high avidity) structures being formed. This is because the antigen may be bound by several antibodies, each recognizing a different epitope. Polyclonal antibodies are therefore ideal for immunoprecipitation experiments.Further Useful ReadingHow we improve the affinity of our recombinant monoclonal antibodies generated using HuCAL technology through affinity maturation。

Affinity and Avidity of AntibodiesAntibody Affinityantigen Affinity measures the strength of interaction between an epitope and an antibody’s binding site. It is defined by the same basic thermodynamic principles that govern any reversible biomolecular interaction:o K A = affinity constanto[Ab] = molar concentration of unoccupied binding sites on the antibodyo[Ag] = molar concentration of unoccupied binding sites on the antigeno[Ab-Ag] = molar concentration of the antibody-antigen complexIn other words, K A describes how much antibody-antigen complex exists at the point when equilibrium is reached. The time taken for this to occur depends on rate of diffusion and is similarfor every antibody. However, high-affinity antibodies will bind a greater amount of antigen in a shorter period of time than low-affinity antibodies. K A can therefore vary widely for antibodies from below 105 mol-1 to above 1012 mol-1, and can be influenced by factors including pH, temperature and buffer composition.The affinity of monoclonal antibodies can be measured accurately because they are homogeneous and selective for a single epitope. Polyclonal antibodies are heterogeneous and will contain a mixture of antibodies of different affinities recognizing several epitopes –therefore only an average affinity can be determined.Antibody AvidityAvidity gives a measure of the overall strength of an antibody-antigen complex. It is dependenton three major parameters:o Affinity of the antibody for the epitope (see above)o Valency of both the antibody and antigeno Structural arrangement of the parts that interactAll antibodies are multivalent e.g. IgGs are bivalent and and IgMs are decavalent. The greater an immunoglobulin’s valency (number of antigen binding sites), the greater the amount of antigen it can bind. Similarly, antigens can demonstrate multivalency because they can bind to more thanone antibody. Multimeric interactions between an antibody and an antigen help their stabilization.A favorable structural arrangement of antibody and antigen can also lead to a more stable antibody-antigen complex as illustrated in Figures 1 and 2.Figure 1. An immobilized antigen (a high local concentration of available epitopes) provides more opportunity for the antibody-antigen complex to form than free antigen in solution over the same time period. Once the first antigen binding arm of an antibody attaches to an antigen on a solid support, the chances of a bivalent interaction are greatly improved. Many immunoassays like Western blotting and ELISA exploit this principle.Figure 2. When an antigen is mixed with a polyclonal antibody, multivalent interactions may leadto large, stable (high avidity) structures being formed. This is because the antigen may be boundby several antibodies, each recognizing a different epitope. Polyclonal antibodies are therefore ideal for immunoprecipitation experiments.Further Useful Readingo How we improve the affinity of our recombinant monoclonal antibodies generated using HuCAL? technology through affinity maturation。

抗原抗体反应：是指抗原与相应抗体在体内或体外发生的特异性结合反应。

抗原抗体间的结合力涉及静电引力、范德华力、氢键和疏水作用力，其中疏水作用力最强，它是在水溶液中两个疏水基团相互接触，由于对水分子的排斥而趋向聚集的力。

亲和性（affinity）：是指抗体分子上一个抗原结合点与一个相应抗原表位（AD）之间的结合强度，取决于两者空间结构的互补程度。

亲合力（avidity）：是指一个完整抗体分子的抗原结合部位与若干相应抗原表位之间的结合强度，它与亲和性、抗体的结合价、抗原的有效AD数目有关。

抗原抗体反应的特点：特异性、可逆性、比例性、阶段性。

带现象（zone phenomenon）：一种抗原-抗体反应的现象。

在凝集反应或沉淀反应中，由于抗体过剩或抗原过剩，抗原与抗体结合但不能形成大的复合物，从而不出现肉眼可见的反应现象。

抗体过量称为前带，抗原过量称为后带。

免疫原（immunogen）：是指能诱导机体免疫系统产生特异性抗体或致敏淋巴细胞的抗原。

免疫佐剂（immuno adjustvant）：简称佐剂，是指某些预先或与抗原同时注入体内，可增强机体对该抗原的免疫应答或改变免疫应答类型的物质。

半抗原（hapten）：又称不完全抗原，是指仅具有与抗体结合的能力(抗原性)，而单独不能诱导抗体产生（无免疫原性）的物质。

当半抗原与蛋白质载体结合后即可成为完全抗原。

载体（carrier）：结合后能给予半抗原以免疫原性的物质。

载体效应：初次免疫与再次免疫时，只有使半抗原结合在同一载体上，才能使机体产生对半抗原的免疫应答，该现象称为~。

单克隆抗体（McAB）：将单个B细胞分离出来，加以增殖形成一个克隆群落，该B细胞克隆产生的针对单一表位、结构相同、功能均一的抗体，即~。

多克隆抗体（PcAb）：天然抗原分子中常含多种不同抗原特异性的抗原表位，以该抗原物质刺激机体免疫系统，体内多个B细胞克隆被激活，产生含有针对不同抗原表位的免疫球蛋白，即~基因工程抗体（GEAb）：是利用DNA重组及蛋白工程技术，从基因水平对编码抗体的基因进行改造和装配，经导入适当的受体细胞后重新表达的抗体。

Affinity and Avidity of AntibodiesAntibody Affinityantigen Affinity measures the strength of interaction between an epitope and an antibody’s binding site. It is defined by the same basic thermodynamic principles that govern any reversible biomolecular interaction:o K A = affinity constanto[Ab] = molar concentration of unoccupied binding sites on the antibodyo[Ag] = molar concentration of unoccupied binding sites on the antigeno[Ab-Ag] = molar concentration of the antibody-antigen complexIn other words, K A describes how much antibody-antigen complex exists at the point when equilibrium is reached. The time taken for this to occur depends on rate of diffusion and is similarfor every antibody. However, high-affinity antibodies will bind a greater amount of antigen in a shorter period of time than low-affinity antibodies. K A can therefore vary widely for antibodies from below 105 mol-1 to above 1012 mol-1, and can be influenced by factors including pH, temperature and buffer composition.The affinity of monoclonal antibodies can be measured accurately because they are homogeneous and selective for a single epitope. Polyclonal antibodies are heterogeneous and will contain a mixture of antibodies of different affinities recognizing several epitopes –therefore only an average affinity can be determined.Antibody AvidityAvidity gives a measure of the overall strength of an antibody-antigen complex. It is dependenton three major parameters:o Affinity of the antibody for the epitope (see above)o Valency of both the antibody and antigeno Structural arrangement of the parts that interactAll antibodies are multivalent e.g. IgGs are bivalent and andIgMs are decavalent. The greater an immunoglobulin’s valency (number of antigen binding sites), the greater the amount of antigen it can bind. Similarly, antigens can demonstrate multivalency because they can bind to more thanone antibody. Multimeric interactions between an antibody and an antigen help their stabilization.A favorable structural arrangement of antibody and antigen can also lead to a more stable antibody-antigen complex as illustrated in Figures 1 and 2.Figure 1. An immobilized antigen (a high local concentration of available epitopes) provides more opportunity for the antibody-antigen complex to form than free antigen in solution over the same time period. Once the first antigen binding arm of an antibody attaches to an antigen on a solid support, the chances of a bivalent interaction are greatly improved. Many immunoassays like Western blotting and ELISA exploit this principle.Figure 2. When an antigen is mixed with a polyclonal antibody, multivalent interactions may leadto large, stable (high avidity) structures being formed. This is because the antigen may be boundby several antibodies, each recognizing a different epitope. Polyclonal antibodies are therefore ideal for immunoprecipitation experiments.Further Useful ReadingHow we improve the affinity of our recombinant monoclonal antibodies generated usingHuCAL technology through affinity maturation。

收稿日期：2012－04－25作者简介：汤代国（1972—），男，编辑，研究方向：医学期刊编辑学。

医学期刊编校中容易混淆的字与词辨析汤代国1，喻俊2（1．《腹部外科》编辑部，湖北武汉430014；2．《中华器官移植杂志》编辑部，湖北武汉430014）摘要：对医学期刊编校中容易混淆的字与词进行文献综述和归纳，对每组词进行辨析，并结合全国科学技术名词审定委员会公布的科技名词，对统一规范标准按规定正确使用，以便尽最大努力减少错别字。

关键词：医学期刊；词语辨析；专业术语中图分类号：G232．2；R-61文献标志码：A文章编号：1673-0143（2012）04-0143-03文字差错主要有易混淆的字与词，名词术语不规范，多字和漏字，数字、简繁字混用等等，许多属同音、近音、形似错用，其中，易混淆的字与词出错概率较高［1］。

不管是作者撰稿还是编辑编校过程中有些词正确区分使用确实很困难，而消灭期刊中的错别字是编辑加工中的一项重要工作，为此，现将医学期刊编辑工作中遇到的易混淆的字与词进行归纳，并结合文献复习综述如下，以供业内同仁参考。

1“分辨率”与“分辨力”医学影像学专业中常用，容易混淆。

“分辨率”定义是指某种设备或材料在单位长度内能够分辨的点或线的数量。

在《物理学名词》（1996年版）中“分辨率”对应的英文为“resolution ”，而没有“分辨力”，只有“分辨本领”一词，对应的英文为“resolving power ”，也可解释为“分辨能力”。

因此，应该用“分辨能力”或“分辨本领”来代替“分辨力”，而要对“分辨能力”进行定量分析时，可根据情况用“分辨率”或“分辨率极限”（指可分辨对象的最小极限）来表示［2］。

2“病死率”和“死亡率”两者的区别在于所用的分子可能相同，但分母不同。

某病病死率=死于某病人数/某病治疗人数ˑ100%；死亡率=某年内死亡总人数/同年平均人口数ˑ1000ɢ。

病死率表示受治病人中死亡的频率，反映疾病的严重程度和预后；而死亡率则提示该病对人群所造成威胁的严重程度，作为评价公众健康状况的一种指标。

名解1、抗原抗体反应：抗原与相应抗体发生特异性结合的反应。

2、亲和性（affinity）：是抗体分子上一个抗原结合点与相应的抗原决定簇之间的相适应而结合的强度，是抗原与抗体间固有的结合力。

3、亲合力（avidity）：是指一个抗体分子与整个抗原表位之间结合的强度，与抗体结合价直接相关。

4、免疫原(immunogen)是能诱导机体免疫系统产生特异性抗体或致敏淋巴细胞，并能与抗体或致敏淋巴细胞发生特异性反应的抗原。

5、免疫佐剂（immunoadjuvant）：预先或与抗原同时注入体内，可增强机体对该抗原的免疫应答或改变免疫应答的类型的物质称为免疫佐剂,简称佐剂（adjuvant）6、多克隆抗体(polyclonal antibody,pcAb)：天然抗原刺激多种B淋巴细胞克隆产生的多种抗体的混合物7、抗血清：将免疫原按照一定的免疫程序免疫动物，一定时间后，采集动物血液，分离得到含有抗体的血清，称为抗血清。

8、单克隆抗体：通过B细胞杂交瘤技术，获得特异性针对单一表位、结构相同、功能均一的抗体，称为单克隆抗体。

9、基因工程抗体是应用DNA重组及蛋白质工程技术，从基因水平对编码抗体基因按不同需要进行改造和装配，经导入适当的受体细胞后重新表达的抗体。

10、不完全抗体：是指分子量小，虽能与抗原牢固结合，但不能起桥联作用引起可见凝集现象的抗体。

这种不可见的抗原抗体反应称为不完全反应。

如IgG类抗体。

结果判断：以定性试验为主，也可半定量。

11、凝集反应是指细菌和红细胞等颗粒性抗原或表面包被可溶性抗原（或抗体）的颗粒性载体与相应抗体（或抗原）特异性结合后，在适当电解质存在下，出现肉眼可见的凝集现象。

反应中的抗原称为凝集原，抗体称为凝集素。

12、沉淀反应是指可溶性抗原与相应抗体在适当条件下发生特异性结合而出现可见的沉淀现象，其特性与经典的抗原抗体反应相同。

形成的沉淀为IC（抗原抗体复合物）。

13、效价(titer)是指反映抗血清中有效抗体含量的相对参数，即抗血清稀释至能与抗原发生有效反应的最大稀释度。

Aαβ-T cell, αβ-T细胞：表达αβ-TCR的T细胞，占外周血中成熟T细胞总数的90%左右。

Acquired immune response，获得性免疫应答：主要由T和B淋巴细胞所介导的抗原特异性免疫应答，包括细胞免疫应答和体液免疫应答两部分，亦称adaptive immune response或specific immune response（特异免疫应答），具有免疫记忆性。

Acquired immunity，获得性免疫：机体在被外来抗原免疫后所获得的抗原特异性免疫状态。

当机体再次遇到该抗原时将能够做出更为迅速而有效的免疫应答。

亦称adaptive immunity。

Active immunization，主动免疫：将外来抗原（常配以佐剂）注入宿主体内以诱导获得性免疫应答的过程，与被动免疫（passive immunization）反义。

Acquired immunodeficiency syndrome (AIDS)，获得性免疫缺陷综合征（艾滋病）：由人免疫缺陷病毒（HIV）感染所引起的免疫缺陷性疾病。

晚期患者体内的CD4+T淋巴细胞极度减少，对各种机会感染易感，并伴有一些罕见的肿瘤，如Kaposi肉瘤和Burkitt淋巴瘤等。

Acute-phase protein，急性期蛋白：一组具有抗感染和辅助组织修复作用的血清蛋白（如MBP和CRP 等），多由肝脏合成，其血清浓度在病原微生物感染或者组织损伤之后迅速大幅度增加。

Adenosine deaminase (ADA)，腺苷脱氨酶：在细胞代谢过程中催化腺苷（adenosine）和2'-脱氧腺苷脱氨分别成为肌苷（inosine）和2'-脱氧肌苷的酶。

ADA基因突变导致脱氧腺苷和dATP在细胞内积蓄并影响淋巴细胞发育，从而引起常染色体隐性遗传性SCID。

Adherent cell，黏附细胞：在体外能够黏于塑料或者玻璃表面的细胞，又为贴壁细胞，如单核巨噬细胞和某些上皮细胞。