医学免疫学试卷B和答案

苏州大学《免疫学》B卷

一、问答题（8’×5＝40）

1. 试比较HLA I类、II类分子的结构、组织分布和功能特点。

2. 简述I型超敏反应的发生过程及机制并举例说明。

3.简述机体抗肿瘤的免疫效应机制。

4.补体活化的旁路途径和终末途径，以及终末途径的杀伤机制。

5.简述免疫球蛋白的三种血清型。

苏州大学《免疫学》B卷参考答案共3 页

一、名词解释(4’×15＝60)

1．免疫应答：指机体受抗原性异物刺激后，体内免疫细胞发生一系列反应以排除抗原性异物的生理过程。主要包括抗原呈递细胞对抗原的加工、处理和呈递，以及抗原特异性淋巴细胞的活化、增生、分化，进而产生免疫效应的过程。

2．Positive selection of T cells: T cells that express a TCR that can bind weakly to self MHC are spared from death and are positively selected to survive.

3．lymphocyte traffic and recirculation

Lymphocytes produced in the primary lymphoid organs (thymus-T, bone marrow-B) migrate via the bloodstream to the secondary lymphoid organs/tissues where they carry out the function. They do not stay in one site but continually recirculate through the body in search of antigens.

4．Tc are CD8+ cells: also called cytotoxic T cells which kill virally infected cells. Once activated cytotoxic T cells act on target cells infected pathogen and kill them by apoptosis (through porferin depended killing and fas depended killing). This stops intracellular pathogens reproducing and further infecting host cells.

5．Co-stimulatory molecule：共刺激分子。T细胞的完全活化同时需要两个信号，第一信号来自TcR与MHC递呈的抗原肽；第二信号来自共刺激分子，如T细胞的CD28分子与APC 上的B7分子结合诱导T细胞增殖和淋巴因子的分泌。

6．Interferons are proteins involved in protection against viral infections. The two kinds of interferon, type I and type II, have different cellular origins and mediate a range of different activities. They interfere with viral replication but also are signaling molecules between cells. 7．ITIM：免疫受体酪氨酸抑制基序。是免疫细胞表面的抑制性调节分子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：在氨基酸上游为侧链体积较大的氨基酸如异亮氨酸或V，其下游第三个氨基酸为亮氨酸。ITIM基序中的酪氨酸是磷酸酯酶的作用位点，被去磷酸后导致细胞的抑制。

8．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.

9．TCR-CD3 complex:A TCR complex is composed of one heterodimeric TCR, plus a 5-polypeptide CD3 complex which is involved in cell signalling for T cell activation. CD3 is the activation complex for the TCR. The TCR only recognizes antigen/MHC complex expressed on the surface of cells. Binding of antigen/MHC to the TCR stimulates CD3. CD3 then sends an activation signal to the inside of the T cell.

10．Affinity maturation ：antibodies produced in the secondary response usually have higher

affinity for (tighter binding to) the antigen than those produced in the primary response. 11．Allograft：Allograft is tissue transferred between genetically different members of the same species. In mice, an allograft is performed by transferring tissue or an organ from one strain to another. In humans, organ grafts from one individual to another are allografts unless the donor and recipient are identical twins.

12．TSA ：Tumor specific antigens (TSA) are unique to tumor cells but rare, which are qualitative differences in antigens associated with normal vs tumor cells. 13．Hypersensitivity ：In some situations, immune responses (especially to some antigens) can lead to more severe tissue damaging reactions (immunopathology). This overreactivity by the immune system to antigens is often referred to as hypersensitivity.

14．Antigen: Substances that are recognized by a particular immunoglobulin or TCR, and so can serve as the target of an immune response, are called antigens.

15．Cytokine:Many critical interactions among cells of the immune system are controlled by soluble mediators, which are called cytokine.

二、问答题（8’×5＝40）

1. 试比较HLA I类、II类分子的结构、组织分布和功能特点。

答：

(1 x 8分)

2. 简述I型超敏反应的发生过程及机制。

答：致敏阶段：抗原进入机体后，诱发机体产生IgE并结合到靶细胞上的过程。（2分）

激发阶段：相同变应原再次进入机体时，通过与致敏肥大细胞/嗜碱粒细胞表面IgE抗体特异性结合，使之脱颗粒，释放生物活性介质的阶段。生物活性介质包括组胺，激肽原酶，LTs, PAF, PGD2等。（3分）

效应阶段：生物活性介质作用于效应组织和器官，引起局部或全身过敏反应的阶段。表现为毛细血管扩张，通透性增加，平滑肌收缩，腺体分泌增多等临床症状。（3分）

3. 简述机体抗肿瘤的免疫效应机制。

答：机体抗肿瘤的免疫效应以细胞免疫为主，体液免疫为协同作用。

效应T细胞的抗肿瘤作用：（2分）

在控制具有免疫原性肿瘤细胞的生长中，抗原活化的T细胞特异地杀伤、溶解带有相应抗原的肿瘤细胞。其中包括MHC I类抗原限制的CD8+ 细胞毒性T淋巴细胞和MHC II类抗原限制的CD4+ 辅助性T淋巴细胞。

CD8+CTL杀伤肿瘤细胞的机制