ENA(extractable nuclear antigens)

Text 2
"Ouch!" you cry as your doctor "stabs" you in a finger or in that sensitive spot on the inside of your elbow opposite your elbow. "Is the sharp, if momentary, pain necessary" You wonder as the doctor takes a sample of your blood. What is she up to anyway What are blood tests for
Your blood is a vital part of your body. It picks up oxygen in your lungs and carries it to your cells, which use the oxygen to produce energy. It carries wastes away from your cells, It carries white blood cells and disease-fighting chemicals called antibodies to places where foreign invaders such as bacteria and viruses are causing infections. The white blood cells gobble up the invaders, and the antibodies knock them out.
Your blood also carries food from your stomach and small intestine to all parts of your body. Clearly, a large loss of blood from an accident or disease can have serious consequences.
So can an imbalance of the blood’ s parts. For example, a low concentration of white cells reduces the body’ s ability to fight infection. A low concentration of oxygen-carrying red cells robs the body of energyreleasing oxygen.
Suppose you lost a lot of blood, what would a doctor do Replace the blood quickly as possible by giving you a transfusion of blood donated by another person. But the doctor can’ t use just anyone’s blood. The donor’s blood has to be of a type that won’t be destroyed by your blood. Blood type What’s that
Remember the blood your doctor took from you Well, some of that blood may have been used to find your blood type--A, B, AB, or O. Each of us has one of these basic blood types (plus a number of subtypes). People with a certain type can receive blood of only certain other types.
To find your blood type, the doctor sends your blood to a laboratory. There your red cells are separated from the other parts of your blood. These cells may have certain antigens (special proteins) on their surfaces--" A "antigens and/or "B" antigens. If your red cells have "A" antigens you are type A, "B" antigens make you type B both "A" and "B" antigens make you type AB, neither "A" nor "B" antigens makes you type O. How do you find those antigens
A lab technician mixes your red blood cells with two kinds of blood serum. One contains anti-A antibodies. The other kind contains anti-B antibodies. An antibody is a substance that "attacks" a particular antigen, in this case "A" or "B" antigens.
The technician taken looks at each mixture under a microscope to see what will happen to your blood cells. Certain mixtures may make your red cells clump together. By finding which mixtures do this and which do not, the technician can figure out your blood type.
But blood typing isn’t the only reason to have a blood test taken. It can also check for signs of infection. How When you have an infection, especially a serious one, the number of white blood cells soars. This is normal response of your body to an invasion of germs.
This time, a sample of blood goes to the lab for a CBC--complete blood count. A technician will examine your blood under a microscope--counting the white cells in a small marked-off area. If the number is much higher than it ought to be, the doctor may need to treat you to be sure the infection doesn’t spread.
Other blood tests can determine the concentration of various chemicals in your blood or the variety and types of blood cells circulating in the blood. The information hidden in a drop of blood may lead a doctor to suggest ways to treat. Or avoid dangerous health conditions.
Was the stick in the finger or arm necessary If protecting yourself from danger is necessary, the answer has got to be--yes!

From parA．7 we may draw the conclusion that（）

A:your blood type is not decided by your red cells B:your blood type is decided by the antigens in your red cells C:your blood type is decided by the A, B or AB antigens D:your blood type is decided by the different kind of serum

On Antibodies Substances foreign to the body, such as disease-causing bacteria and viruses and other infectious agents, are recognized by the body s immune system as invaders. Our natural defenses against these infectious agents are antibodies, proteins that seek out the antigens (抗原) and help destroy them. Antibodies have two very useful characteristics. First, they are extremely specific; that is, each antibody binds to and attacks one particular antigen. Second, some antibodies, once activated by the occurrence of a disease, continue to confer resistance against that disease. Classic example are the antibodies to the childhood diseases of chickenpox(水痘) and measles. The second characteristic of antibodies makes it possible to develop vaccines. A vaccine (痘苗) is a preparation of killed or weakened bacteria or viruses that, when introduced into the body, stimulates the production of antibodies against the antigens it contains. It is the first trait of antibodies, their specificity, that makes monoclonal antibody technology so valuable. Not only can antibodies be used therapeutically(在治疗上), to protect against disease; they can also help to .diagnose a wide variety of illnesses, and can detect the presence of drugs, viral and bacterial products, and other unusual or abnormal substances in the blood. Given such a diversity of uses for these diseased-fighting substances, their production in pure quantities has long been the focus of scientific investigation. The conventional method was to inject a laboratory animal with an antigen and then, after antibodies had been formed, collect those antibodies from the blood serum(血清) (Antibody containing blood serum is called antiserum (抗血清)). There are two problems with this method: It yields antiserum that contains undesired substances, and it provides a very small amount of usable antibody. Monoclonal antibody technology allows us to produce large amounts of pure antibodies. in the following way: we can obtain cells that produce antibodies naturally; we also have available a class of cells that can grow continually in cell culture (培养). If we form a hybrid (混血儿) that combines the characteristic of "immortality"(永生)with the ability to produce the desired substance, we would have, in effect, a factory to produce antibodies that work around the clock. In monoclonal antibody technology, tumor cells that can replicate (重复) endlessly are fused with mammalian cells that produce an antibody. The result of this cell fusion is a "hybridoma" (杂交瘤), which will continually produce antibodies. These antibodies are called monoclonal because they come from only one type of cell, the hybridoma cell; antibodies produced by conventional methods, on the other hand, are derived from preparations containing many kinds of cells, and hence are called polyclonal. An example of how monoclonal antibodies are derived is described below. A myeloma is a tumor of the bone marrow (骨髓) that can be adapted to grow permanendy in cell culture. When myeloma cells were fused with antibody-producing mammalian spleen cells, it was found that the resulting hybrid cells, or hybridomas, produced large amounts of monoclonal(骨髓瘤) antibody. This product of cell fusion combined the desired qualities of the two different types of cells: the ability to grow continually, and the ability to produce large amounts of pure antibody. Because selected hybrid cells produce only one specific antibody, they are more pure than the polyclonal antibodies produced by conventional techniques. They are potentially more effective than conventional drugs in fighting disease, since drugs attack not only the foreign substance but the body’s own cells as well, sometimes producing undesirable side effects such as nausea(恶心) and allergic reactions. Monoclonal antibodies attack the target molecule and only the target molecule, with no or greatly diminished side effects. Which of the following substances is not an invader to the body’s immune system?

A:disease-causing bacteria B:disease-causing viruses C:antigens D:protein

The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communication network consisting of millions and millions of cells. Organized into sets and subsets,these cells pass information back and forth like clouds of bees flying around a hive (蜂巢). The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and no self. When immune defenders encounter cells or organisms carrying foreign or nonself molecules,the immune troops move quickly to eliminate the intruders(入侵者). Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a selfmarker. Rather, immune cells and other body cells coexist peaceably in s state known as self-toler-ance. When a normally functioning immune system attacks a nonself molecule, the system has the ability to"remember" the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies(抗体) passed during lactation (哺乳期]), this so called immune system memory is not inherited. Despite the occurrence of a virus in your family,your immune system must "learn" from experience with the many millions of distinctive nonself molecules in the sea of microbes (微生物)in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each nonself invader.
Any substance capable of triggering an immune response is called an antigen(抗原). Antigens are not to be confused with allergens (过敏原), which are most often harmless substances that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium or even a portion or product of one of these organisms. Tissues or cells from another individual also act as antigens;because the immune system recognizes transplanted tissues as foreign, it rejects them. The body will even reject nourishing proteins unless they are first brokendown by the digestive system into their primary, nonantigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitopes(抗原表位),which protrude(突 出) from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitopes on their surface; some may even carry several hundreds. Some epitopes will be more effective than others at stimulating an immune response. Only in abnormal situation does the immune system wrongly identify self as nonself and execute a misdirected immune attack.

Which of the following statements is true（　）

A:Allergens are usually harmful substances. B:Antigens can trigger an immune response. C:People with antigens do not suffer from obvious responses. D:There is no difference between an antigen and an allergen.

The immune system is equal in complexity to the combined intricacies of the brain and nervous system. The success of the immune system in defending the body relies on a dynamic regulatory communication network consisting of millions and millions of cells. Organized into sets and subsets,these cells pass information back and forth like clouds of bees flying around a hive (蜂巢). The result is a sensitive system of checks and balances that produces an immune response that is prompt, appropriate effective, and self-limiting.
At the heart of the immune system is the ability to distinguish between self and no self. When immune defenders encounter cells or organisms carrying foreign or nonself molecules,the immune troops move quickly to eliminate the intruders(入侵者). Virtually every body cell carries distinctive molecules that identify it as self. The body’s immune defenses do not normally attack tissues that carry a selfmarker. Rather, immune cells and other body cells coexist peaceably in s state known as self-toler-ance. When a normally functioning immune system attacks a nonself molecule, the system has the ability to"remember" the specifics of the foreign body. Upon subsequent encounters with the same species of molecules, the immune system reacts accordingly. With the possible exception of antibodies(抗体) passed during lactation (哺乳期]), this so called immune system memory is not inherited. Despite the occurrence of a virus in your family,your immune system must "learn" from experience with the many millions of distinctive nonself molecules in the sea of microbes (微生物)in which we live. Learning entails producing the appropriate molecules and cells to match up with and counteract each nonself invader.
Any substance capable of triggering an immune response is called an antigen(抗原). Antigens are not to be confused with allergens (过敏原), which are most often harmless substances that provoke the immune system to set off the inappropriate and harmful response known as allergy. An antigen can be a virus, a bacterium or even a portion or product of one of these organisms. Tissues or cells from another individual also act as antigens;because the immune system recognizes transplanted tissues as foreign, it rejects them. The body will even reject nourishing proteins unless they are first brokendown by the digestive system into their primary, nonantigenic building blocks. An antigen announces its foreignness by means of intricate and characteristic shapes called epitopes(抗原表位),which protrude(突 出) from its surface. Most antigens, even the simplest microbes, carry several different kinds of epitopes on their surface; some may even carry several hundreds. Some epitopes will be more effective than others at stimulating an immune response. Only in abnormal situation does the immune system wrongly identify self as nonself and execute a misdirected immune attack.
Which of the following statements is true

A:Allergens are usually harmful substances. B:Antigens can trigger an immune response. C:People with antigens do not suffer from obvious responses. D:There is no difference between an antigen and an allergen.

On Antibodies Substances foreign to the body, such as disease-causing bacteria and viruses and other infectious agents, are recognized by the body s immune system as invaders. Our natural defenses against these infectious agents are antibodies, proteins that seek out the antigens (抗原) and help destroy them. Antibodies have two very useful characteristics. First, they are extremely specific; that is, each antibody binds to and attacks one particular antigen. Second, some antibodies, once activated by the occurrence of a disease, continue to confer resistance against that disease. Classic example are the antibodies to the childhood diseases of chickenpox(水痘) and measles. The second characteristic of antibodies makes it possible to develop vaccines. A vaccine (痘苗) is a preparation of killed or weakened bacteria or viruses that, when introduced into the body, stimulates the production of antibodies against the antigens it contains. It is the first trait of antibodies, their specificity, that makes monoclonal antibody technology so valuable. Not only can antibodies be used therapeutically(在治疗上), to protect against disease; they can also help to .diagnose a wide variety of illnesses, and can detect the presence of drugs, viral and bacterial products, and other unusual or abnormal substances in the blood. Given such a diversity of uses for these diseased-fighting substances, their production in pure quantities has long been the focus of scientific investigation. The conventional method was to inject a laboratory animal with an antigen and then, after antibodies had been formed, collect those antibodies from the blood serum(血清) (Antibody containing blood serum is called antiserum (抗血清)). There are two problems with this method: It yields antiserum that contains undesired substances, and it provides a very small amount of usable antibody. Monoclonal antibody technology allows us to produce large amounts of pure antibodies. in the following way: we can obtain cells that produce antibodies naturally; we also have available a class of cells that can grow continually in cell culture (培养). If we form a hybrid (混血儿) that combines the characteristic of "immortality"(永生)with the ability to produce the desired substance, we would have, in effect, a factory to produce antibodies that work around the clock. In monoclonal antibody technology, tumor cells that can replicate (重复) endlessly are fused with mammalian cells that produce an antibody. The result of this cell fusion is a "hybridoma" (杂交瘤), which will continually produce antibodies. These antibodies are called monoclonal because they come from only one type of cell, the hybridoma cell; antibodies produced by conventional methods, on the other hand, are derived from preparations containing many kinds of cells, and hence are called polyclonal. An example of how monoclonal antibodies are derived is described below. A myeloma is a tumor of the bone marrow (骨髓) that can be adapted to grow permanendy in cell culture. When myeloma cells were fused with antibody-producing mammalian spleen cells, it was found that the resulting hybrid cells, or hybridomas, produced large amounts of monoclonal(骨髓瘤) antibody. This product of cell fusion combined the desired qualities of the two different types of cells: the ability to grow continually, and the ability to produce large amounts of pure antibody. Because selected hybrid cells produce only one specific antibody, they are more pure than the polyclonal antibodies produced by conventional techniques. They are potentially more effective than conventional drugs in fighting disease, since drugs attack not only the foreign substance but the body’s own cells as well, sometimes producing undesirable side effects such as nausea(恶心) and allergic reactions. Monoclonal antibodies attack the target molecule and only the target molecule, with no or greatly diminished side effects. Which of the following substances is not an invader to the body’s immune system?

A:disease-causing bacteria B:disease-causing viruses C:antigens D:protein

On Antibodies Substances foreign to the body, such as disease-causing bacteria and viruses and other infectious agents, are recognized by the body s immune system as invaders. Our natural defenses against these infectious agents are antibodies, proteins that seek out the antigens (抗原) and help destroy them. Antibodies have two very useful characteristics. First, they are extremely specific; that is, each antibody binds to and attacks one particular antigen. Second, some antibodies, once activated by the occurrence of a disease, continue to confer resistance against that disease. Classic example are the antibodies to the childhood diseases of chickenpox(水痘) and measles. The second characteristic of antibodies makes it possible to develop vaccines. A vaccine (痘苗) is a preparation of killed or weakened bacteria or viruses that, when introduced into the body, stimulates the production of antibodies against the antigens it contains. It is the first trait of antibodies, their specificity, that makes monoclonal antibody technology so valuable. Not only can antibodies be used therapeutically(在治疗上), to protect against disease; they can also help to .diagnose a wide variety of illnesses, and can detect the presence of drugs, viral and bacterial products, and other unusual or abnormal substances in the blood. Given such a diversity of uses for these diseased-fighting substances, their production in pure quantities has long been the focus of scientific investigation. The conventional method was to inject a laboratory animal with an antigen and then, after antibodies had been formed, collect those antibodies from the blood serum(血清) (Antibody containing blood serum is called antiserum (抗血清)). There are two problems with this method: It yields antiserum that contains undesired substances, and it provides a very small amount of usable antibody. Monoclonal antibody technology allows us to produce large amounts of pure antibodies. in the following way: we can obtain cells that produce antibodies naturally; we also have available a class of cells that can grow continually in cell culture (培养). If we form a hybrid (混血儿) that combines the characteristic of "immortality"(永生)with the ability to produce the desired substance, we would have, in effect, a factory to produce antibodies that work around the clock. In monoclonal antibody technology, tumor cells that can replicate (重复) endlessly are fused with mammalian cells that produce an antibody. The result of this cell fusion is a "hybridoma" (杂交瘤), which will continually produce antibodies. These antibodies are called monoclonal because they come from only one type of cell, the hybridoma cell; antibodies produced by conventional methods, on the other hand, are derived from preparations containing many kinds of cells, and hence are called polyclonal. An example of how monoclonal antibodies are derived is described below. A myeloma is a tumor of the bone marrow (骨髓) that can be adapted to grow permanendy in cell culture. When myeloma cells were fused with antibody-producing mammalian spleen cells, it was found that the resulting hybrid cells, or hybridomas, produced large amounts of monoclonal(骨髓瘤) antibody. This product of cell fusion combined the desired qualities of the two different types of cells: the ability to grow continually, and the ability to produce large amounts of pure antibody. Because selected hybrid cells produce only one specific antibody, they are more pure than the polyclonal antibodies produced by conventional techniques. They are potentially more effective than conventional drugs in fighting disease, since drugs attack not only the foreign substance but the body’s own cells as well, sometimes producing undesirable side effects such as nausea(恶心) and allergic reactions. Monoclonal antibodies attack the target molecule and only the target molecule, with no or greatly diminished side effects. Which of the following substances is not an invader to the body’s immune system?

A:disease-causing bacteria B:disease-causing viruses C:antigens D:protein