IMMUNITY
Immunity is a state of relative resistance to a disease that develops after exposure to the specific disease-causing agent. People are not born with immunity to diseases, so they must acquire immunity by stimulating B-cell clones to form plasma cells and then antibodies.
免疫力就是接触特定疾病后产生的对该疾病致病因子的相对抵抗力。人并不是生来就对疾病免疫，因此，必须通过刺激B细胞克隆体形成浆细胞以及抗体，从而获得免疫力。
Immunity can be active or passive. 免疫力有主动也有被动。
Active immunity occurs when the body recognizes a foreign protein and begins producing antibodies to react with that specific protein or antigen. After plasma cells are formed to produce antibodies, specific memory cells that produce the same antibodies are created. If the specific foreign protein is introduced into the body again, these memory cells react immediately to release antibodies. This type of immunity is thought to be lifelong.
身体识别外来蛋白质，开始产生抗体来应对特异性蛋白质或抗原，这就是主动免疫。浆细胞生成并产生抗体后，就会生成同一抗体的特异性记忆细胞。如果一旦特定的外来蛋白质再次进入身体，这些记忆细胞就会立即做出反应释放抗体。这种免疫力属于终身免疫力。
Passive immunity occurs when preformed antibodies are injected into the system and react with a specific antigen. These antibodies come from animals that have been infected with the disease or from humans who have had the disease and have developed antibodies. The circulating antibodies act in the same manner as those produced from plasma cells, recognizing the foreign protein and attaching to it, rendering it harmless. Unlike active immunity, passive immunity is limited. It lasts only as long as the circulating antibodies last because the body does not produce its own antibodies. In some cases, the host human responds to the circulating injected antibodies, which are foreign proteins to the host’s body, by producing its own antibodies to the injected antibodies. This results in serum sickness, a massive immune reaction manifested by fever, arthritis, flank pain, myalgia, and arthralgia.
将预成抗体注入身体系统与特异性抗原起反应，这就是被动免疫。这些抗体有的来自已被疾病感染的动物，有的则来自生过病并已产生抗体的人类。循环抗体的作用方式与浆细胞产生的抗体相同：识别外来蛋白质，吸附并使它失去毒害能力。与主动免疫不同的是，被动免疫是有限制的。循环抗体持续多久，被动免疫也就持续多久，因为身体并未产生自己的抗体。在有些情况下，宿主人自身会产生注入抗体的抗体，对注入的循环抗体做出反应，因为宿主而言，循环抗体也属外来蛋白质。这种免疫反应的结果就是血清病，表现为发烧、关节炎、胁腹痛、肌痛和关节痛。
Immunization is the process of artificially stimulating active immunity by exposing the body to weakened or less toxic proteins associated with specific disease-causing organisms. The proteins could be a weakened bacterial cell membrane, the protein coat of a virus, or a virus (protein coat with the genetic fragment that makes up the virus) that has been chemically weakened so that it cannot cause disease. The goal is to cause an immune response without having the patient suffer the full course of a disease.
免疫就是通过身体接触与特定致病生物相关的减毒蛋白质达到人工刺激主动免疫的过程。该蛋白质可以是减毒细菌的细胞膜，即病毒的蛋白外壳，也可以是通过化学减毒、已不会引起疾病的病毒（含有构成病毒的基因片断的蛋白外壳）。目的是引起免疫应答但又不会让患者得病。
Adults may require immunizations in certain situations: exposure, travel to an area endemic for a disease they have not had and have not been immunized against, and occupations that are considered high risk. Children routinely are immunized against many infections that were once quite devastating. For example, smallpox was one of the first diseases against which children were immunized. Today, smallpox is considered to be eradicated worldwide.
成人在特定情况下需要免疫：接触或旅行到某个流行病区，他们本身尚未得过此病，或对此病尚未免疫；以及从事高风险职业。儿童则按常规接种对多种感染产生免疫，这些感染曾经是毁灭性的，如天花，它曾经是儿童免疫的首种疾病之一。如今，天花已经在全球绝迹。
Diphtheria, pertussis, tetanus, Haemophilus influenzae B, hepatitis B, hepatitis A, chickenpox, poliovirus, meningitis, measles, mumps, rotavirus, and rubella are all standard childhood immunizations today. The bacille Calmette-Guérin (BCG) vaccine for tuberculosis is widely used throughout the world in countries with a high incidence of tuberculosis to limit the spread of the disease. However, it is not routinely used in the United States because the incidence of tuberculosis is relatively low and it can induce false-positive tuberculin skin test results. The human papillomavirus (HPV) vaccine is now recommended for girls to protect against several of the viruses that cause many cervical cancers.
标准的儿童免疫包括白喉、百日咳、破伤风、流感嗜血菌B、乙肝、甲肝、水痘、脊髓灰质炎、脑膜炎、麻疹、流行性腮腺炎、轮状病毒和风疹。治疗结核病的卡介苗（BCG）已广泛用于全球结核病发生率较高的国家，限制了疾病的传播。但在美国，它不属于常规疫苗，因为美国的结核病发生率相对较低，它会在结核菌皮肤试验中引起假阳性。人乳头状病毒（HPV）疫苗建议女孩使用，以防御可能引起宫颈癌的多种病毒。
The use of vaccines is not without controversy. Severe reactions, although rare, have occurred, resulting in concerns about the safety of vaccines and their administration, especially in children.
疫苗使用也不是没有争议。有些严重反应尽管罕见，但也引起人们对安全性及其使用的担心，特别是对儿童。
★Vocabulary for Today ★
immunity – n. 免疫力
plasma cells – 浆细胞
active immunity – 主动免疫
foreign protein – 异体蛋白质
memory cells – 记忆细胞
passive immunity – 被动免疫
preformed antibodies – 预成抗体
specific antigen – 特异性抗原
circulating antibodies – 循环抗体
render – v. 提供，使…帮忙等
serum sickness – 血清病
immunization – n. 免疫（法）
weakened – a. 减毒的
protein coat – 蛋白（质）外壳
genetic fragment – 基因片段
immune response – 免疫应答
endemic – a. n. 地方性的，地方病
eradicate – v. 根治，消灭
★Video ★
Active and Passive Immunity
★Test ★
1. A client has a positive reaction to the Mantoux test. The nurse correctly interprets this reaction to mean that the client has:
A. Active tuberculosis.
B. Had contact with Mycobacterium tuberculosis.
C. Developed a resistance to tubercle bacilli.
D. Developed passive immunity to tuberculosis. 2. A client with a fractured right femur has not had any immunizations since childhood. Which of the following biologic products should the nurse administer to provide the client with passive immunity for tetanus?
A. Tetanus toxoid.
B. Tetanus antigen.
C. Tetanus vaccine.
D. Tetanus antitoxin.
答案 Key to Questions
1. B. Had contact with Mycobacterium tuberculosis.
Rationale: A positive Mantoux skin test indicates that the client has been exposed to tubercle bacilli. Exposure does not necessarily mean that active disease exists. A positive Mantoux test does not mean that the client has developed resistance. Unless involved in treatment, the client may still develop active disease at any time. Immunity to tuberculosis is not possible. 2. D. Tetanus antitoxin.
Passive immunity for tetanus is provided in the form of tetanus antitoxin or tetanus immune globulin. An antitoxin is an antibody to the toxin of an organism. Administering tetanus toxoid, antigen, or vaccine would provide active immunity by stimulating the body to produce its own antibodies.
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