苏州大学《免疫学》A卷苏州大学《免疫学》A卷参考答案共3 页一、名词解释1．锚定残基：与MHC结合成复合物的抗原肽往往带有两个或两个以上和MHC 分子凹槽相结合的特定部位，称锚定位，该位置的氨基酸残基称为锚定残基(anchor residue)。
2．Negative selection of T cells: T cells that react strongly to self-antigens on MHC are eliminated. Only those T cells that can react to MHC, but do not bind strongly to self-antigens emerge as mature T cells from the thymus.3．免疫细胞：泛指所有参加免疫应答或与免疫应答有关的细胞及其前身，主要包括造血干细胞、淋巴细胞、单核/巨噬细胞及其他抗原递呈细胞、粒细胞、肥大细胞和红细胞等。
4．抗体分子的类别转换：B细胞所合成的Ig重链的类别由一种（如Igμ）转换为另一种（如Igγ或者Igα）的过程。
类别转换不影响抗体分子的抗原特异性。
5. DCs are required by T cell to enable them to respond to antigens. DCs are most important antigen presenting cells known so far and are the interface of innate and adoptive immunity. Functions: Antigen up-taking in peripheral sites & antigen presentation in lymph nodes.6. ITAM：免疫受体酪氨酸活化基序。
免疫细胞活化相关受体胞浆区所共有的以酪氨酸残基为基础的氨基酸序列基序，其特征为：两个酪氨酸残基被大约13个其它氨基酸残基隔开，其中酪氨酸是蛋白激酶磷酸化位点，被磷酸化后能够与信号转导途径下游的信号分子结合，导致细胞的活化。
7. MALT: The majority (50%) of lymphoid tissue in the human body is located within the lining of the major tracts, including respiratory, digestive and genitourinary tracts. This is because these are the main sites of entry for microbes into the body. These are collectively called the mucosa-associated lymphoid tissues (MALT).8. GVHR:graft versus host reaction. If an immunocompromised host is grafted with foreign immunocompetent lymphoid cells, the immunoreactive T cells in the graft recognize the foreign antigens on the host tissue and cause their damage. GVHR occurs when donor T cells react to host antigens on APCs with sequential activation of donor T cells and monocytes / macrophages causing target organ damage.9. cytokines: Definition: Cytokines are small molecules, secreted by cells in response to a stimulus. Function: As a group, cytokines induce growth, differentiation, chemotaxis, activation and/or enhanced cytotoxity. They are used for strengthening communications between cells.10. Epitope: An epitope is the specific site to which a particular immunoglobulin or TCR binds.11. Idiotype: these are unique antigenic determinants associated with an antigen binding sites of antibodies and are the result of the different amino acid sequences which derermine their specificities.12. Autoimmunity: Autoimmunity is defined as an acquired immune reactivity against self antigens. This response usually produces antoantibodies and antoreactive T cells.13. BCR complex: The BCR complex consists of the antigen receptor, Ig, in association with two other polypeptides, Igαand Igβ. Igαand Igβare signaling molecules for the BCR and are also required for assembly and expression of Ig.14. MHC:The major histocompatibility complex. Although molecules coded for by the MHC were originally identified based on their role in transplant rejection, they actually evolved to present foreign antigens to T cells. Two classes (Class I and II) of MHC genes, closed linked onchromosome 6 in humans, code for human leukocyte antigens (HLA) which are the molecules critical to antigen presentation.15. TAA:Tumor associated antigens are also found on some normal cells, which are the quantitative differences in antigens associated with normal vs tumor cells, such as AFP, CEA.二、问答题（8’×5＝40）1. 简述T细胞识别抗原的双信号学说。
答:2-signal theory for T cell activation: A popular model to explain the requirement of T cell activation is the two-signal hypothesis(2). In this model, signal one is derived from the TCR after triggering by antigenic peptide presented by MHC(2) and signal two is delivered through costimulatory molecules expressed on the surface of T cells, B cells and APCs.(2) with 2 signals T cell express IL-2R alpha chain and secrete more IL-2. IL-2 is T cell growth factor to stimulate T cell proliferation.(2)2. 试述内源性抗原和外源性抗原的提呈过程。
答：内源性(或者I类) 抗原递呈途径(endogenous, or class I, antigen presentation pathway):内源性蛋白质分子在胞浆内被处理并通过MHC-I分子递呈于细胞表面的途径。
外源性(或者II类) 抗原递呈途径(exogenous, or classII, antigen presenting pathway):外源性蛋白质分子在吞噬溶酶体内被处理并通过MHC-II分子递呈于细胞表面的途径（4分）（4分）3. 试述超敏反应的概念、分型和发病机制。
答：答：免疫系统在发挥免疫效应的同时不可避免地给机体带来炎症性损伤，将这种现象称为超敏反应。
（2分）（1.5 4分）4．补体活化的经典途径和终末途径，以及终末途径的杀伤机制。
答：（1）经典途径：1）识别阶段抗原和抗体结合后，抗体发生构想改变，使FC段的补体结合部位暴露，补体C1与之结合并被激活，这一过程被称为补体激活的启动或识别。
（1分）2）活化阶段活化的C1S依次酶解C4，C2，形成具有酶活性的C3转化酶（1分），后者进一步酶解C3并行成C5转化酶（1分），最终引起相同的末端效应。
（2）MAC的组装：C5与C5转化酶的C3B结合，并被裂解成C5A和C5B。
依次于C6，C7结合。
所形成的C5B67复合物，插入浆膜中，进而与C8呈高亲和力结合，形成C5B678。
可于12-15个C9分子联接成C5B-9，即MAC（2分）。
MAC的效应机制：MAC在胞膜上形成的小孔使得小的可溶性分子，离子以及水分子可以自由透过胞膜，但蛋白质之类的大分子却难以从胞浆中逸出，最终导致胞内渗透压降低，细胞溶解。