首页
登录
职称英语
The antigen-antibody immunological reaction used to be regarded as typical o
The antigen-antibody immunological reaction used to be regarded as typical o
游客
2025-04-26
32
管理
问题
The antigen-antibody immunological reaction used to be regarded as typical of immunological responses. Antibodies are proteins synthesized by specialized cells called plasma cells, which are funned by lymphocytes (cells from the lymph system} when an antigen, a substance foreign to the organism’s body, comes in contact with lymphocytes. Two important manifestations of antigen- antibody immunity are lysis, the rapid physical rupture of antigenic cells and the liberation of their contents into the surrounding medium, and phagocytosis, a process in which antigenic particles are engulfed by and very often digested by macrophages and polymorphs. The process of lysis is executed by a complex and unstable blood constituent known as complement, which will not work unless it is activated by a specific antibody; the process of pbagocytosis is greatly facilitated when the particles to be engulfed are coated by a specific antibody directed against them.
The reluctance to abandon this hypothesis, however well it explains specific processes, impeded new research, and for many years antigens and antibodies dominated the thoughts of immunologists so completely that those immunologists overlooked certain difficulties. Perhaps the primary difficulty with the antigen-antibody explanation is the informational problem of how an antigen is recognized and how a structure exactly complementary to it is then synthesized. When molecular biologists discovered, moreover, that such information cannot flow from protein to protein, hut only from nucleic acid to protein, the theory that an antigen itself provided the mold that directed the synthesis of an antibody had to be seriously qualified. The attempts at qualification and the information provided by research in molecular biology led scientists to realize that a second immunological reaction is mediated through the lymphocytes that are hostile to and bring about the destruction of the antigen. This type of immunological response is called cell- mediated immunity.
Recent research in cell-mediated immunity has been concerned not only with the development of new and better vaccines, but also with the problem of transplanting tissues and organs from one organism to another, for although circulating antibodies play a part in the rejection of transplanted tissues, the primary role is played by cell-mediated reactions. During cell-mediated responses, receptor sites on specific lymphoeytes and surface antigens on the foreign tissue cells form a complex that binds the lymphocytes to the tissue. Such lymphocytes do not give rise to antibody- producing plasma cells but themselves bring about the death of the foreign-tissue cells, probably by secreting a variety of substances, some of which are toxic to the tissue cells and some of which stimulate increased phagocyte activity by white blood cells of the macrophage type. Cell-mediated immunity also accounts for the destruction of intracellular parasites. [br] The author most probably believes that the antigen-antibody theory of immunological reaction______.
选项
A、is wrong
B、was accepted without evidence
C、is unverifiable
D、is a partial explanation
答案
D
解析
转载请注明原文地址:https://tihaiku.com/zcyy/4054466.html
相关试题推荐
Theantigen-antibodyimmunologicalreactionusedtoberegardedastypicalo
Theantigen-antibodyimmunologicalreactionusedtoberegardedastypicalo
Theantigen-antibodyimmunologicalreactionusedtoberegardedastypicalo
Theantigen-antibodyimmunologicalreactionusedtoberegardedastypicalo
Onereactiontoalltheconcernabouttropicaldeforestationisablankstare
Onereactiontoalltheconcernabouttropicaldeforestationisablankstare
Onereactiontoalltheconcernabouttropicaldeforestationisablankstare
The______wastypicaloftheLakeDistrict,withhighmountains,lakes,anddee
ThetypicalshoeoftheMiddleAgeswasasoft,clingingmoccasinthatextended
Wasit______theprofessorregardedwithsuchcontempt?A、themwhoB、themwhomC
随机试题
Faithschoolsandacademiesshouldbestrippedoftheirpowertochoosepupi
孕妇女,27岁。第一胎,孕34周。突然无宫缩而阴道大量流水,诊断为胎膜早破。护士
A.必须凭执业医师或执业助理医师的处方才可调配购买和使用的药品 B.临床必需,
对于具有绝缘架空地线的线路,要加强放电间隙的(),确保动作可靠。(A)检
常见汉字编码有()。A.汉字输入码 B.汉字字形码 C.汉字机内码 D.
自我同一性
根据《中华人民共和国合伙企业法》,下列经济主体中,可以成为合伙企业普通合伙人的有
中央银行金融服务的特征有()A:法定性 B:基础性 C:公益性 D:引导性
HEQ22髙频对称长途通信电缆与500kV输电线肿行接近,已知对称电缆远距离供电
(2020年真题)根据《建设工程工程量清单计价规范》,投标人认为招标控制价没有按
最新回复
(
0
)