Chalter 12 Specific Resistance To Infection Flashcards
What are lymphocytes?
Lymphocytes are cells that are involved in both non-specific and specific defence.
Describe lymphocytes in the body.
- About 20-30% of the white cells in the blood are lymphocytes.
- However, these circulating lymphocytes are only a small fraction of the total lymphocytes in the body.
- The combined weight of lymphocytes in a person’s body is over a kilogram.
Where are lymphocytes produced?
- Most lymphocytes are produced in the bone marrow, but they are also produced in lymphoid tissues.
- Lymphocytes roam throughout the body.
- They are able to wander through a tissue and then enter the blood, or the lymph, to be transported to another part of the body where they again enter the tissues.
What are Pathogens/ pathogenic organisms?
Micro-organisms which can cause diseases.
What are Macrophages?
- They are also involved in both non-specific and specific defence.
- They are large phagocytic cells that develop from a type of white blood cell.
- They are able to consume foreign substances and micro-organisms by phagocytosis.
- They are involved in specific defence by alerting the immune system to the presence of foreign material.
What are specific defences?
- Specific defences are those directed towards a particular pathogen.
- They are apart of our immune system.
Give an example of a specific defence.
- If you get infected (or vaccinated) with chickenpox virus, the body will make antibodies to combat that virus.
- Those antibodies are only effective against chickenpox virus and will not work against any other virus or bacterium.
What is the immune system composed of ?
- Different types of cells that occur in most of the organs of the body.
- These cells protect against foreign organisms, a range of alien chemicals, as well as cancerous and other abnormal cells.
- Some of these cells are non-specific, such as phagocytes, which are able to engulf and digest micro-organisms and cell debris.
- However, others such as B cells and T cells only provide protection against a specific micro-organisms or disease-causing substance.
- When these cells react is it called the Immune System.
What is Immune response ?
- It is a homeostatic mechanism.
- When micro-organisms or foreign substances enter the body, the immune response helps to deal with the invasion and restore the internal environment to its normal condition.
What are the 2 parts of the immune response?
- Humoral Response or Antibody-mediated immunity.
2. Cell-mediated response.
What is the function of the Humoral Response?
It involves the production of special proteins called antibodies, which circulate around the body and attack invading agents.
What is the function of the Cell-mediated response?
It involves formation of special lymphocytes that destroy invading agents.
What is the Lymphoid tissue?
- It is involved in both the humoral and cell-mediated responses.
- Most lymphoid tissue is in the lymph nodes but it also occurs in other parts of the body, such as the spleen, the thymus gland and the tonsils.
- Composed of two types of lymphocytes that are involved in the immune response - the B cells and T cells.
What does the B and T cells do?
B cells: Provide antibody-mediated immunity
T cells: Provide cell-mediated immunity.
Where do the B and T cells come from ?
-Both these cells are produced in the bone marrow, and both end up in the lymphoid tissue, but they mature by following two different routes between bone marrow and lymphoid tissue.
Where do the B and T cells end up?
- About half the cells produced by the bone marrow go to the thymus where they mature into T cells before being incorporated into the lymphoid tissues.
- The other half of the cells mature in the bone marrow to become B cells and then also become part of the lymphoid tissues.
How to remember B and T cells?
T cells: They mature in the Thymus
B cells: They mature in the Bone marrow
What is an Antigen?
- It is any substance capable of causing a specific immune response.
- Antigens are large molecules.
- They have many proteins, carbohydrates, lipids or nucleic acid.
- An antigen could be a virus particle or a whole micro-organism, such as a bacterial cell, or part of a bacterium, such as the flagella, cell wall or capsule.
- Toxins produced by bacteria are also antigens.
- Antigens are not necessarily associated with micro-organisms.
- Tissues transplanted from another person, blood cells or a foreign blood group, and such things as pollen grains and egg white contain antigens.
What is the role of Antigens?
- It Triggers Antibody-mediated and cell-mediated immunity.
- Such a substance, introduced to the body, causes the body to produce specific antibodies.
What are Self Antigens and Non-Self Antigens?
- Self Antigens - They are large molecules in a person’s own body which do not cause and immune response.
- Non-Self Antigens - Foreign compounds that do trigger an immune response.
- > The immune system becomes programmed to distinguish between self-antigens and non-self antigens before birth. From then on, it only attacks non-self antigens.
What is an antibody?
-It is a specialised protein that is produced in response to a non-self-antigen.
What are Immunoglobulins?
- Group of proteins in which the antibodies belong to, often represented as Ig.
- There are 5 classes of these antibodies, which vary in their structure and are designated IgA, IgD, IgE, IgG and IgM.
Why are the active sites on the antibody and antigen molecules said apply the Lock and Key analogy?
- The antibody produced in response to an antigen can combine with that antigen to form an antigen-antibody complex.
- Antigen molecules have specific active sites and at these sites the antibody can combine with the antigen.
- Each antibody can combine with only ONE particular antigen, in the same way that a key will only open a particular lock.
What is Antibody-mediated immunity?
- It is the humoral response which involves the production and release of antibodies into the blood and lymph.
- It provides resistance to viruses, bacteria and bacterial toxins before these micro-organisms or substances enter the body’s cells.
Where do clones come from ?
- Lymphoid tissue contains thousands of different types of B cells.
- Each type is capable of responding to a specific antigen.
- When an antigen activates B cells, they enlarge and divide into a group of cells called a clone.
What are Plasma cells?
Most of the clone become plasma cells, which secrete the specific antibody capable of attaching to the active site of the antigen.
What is the role of the antibodies secreted by the plasma cells?
These antibodies circulate in the blood, lymph and extracellular fluid to reach the site of the invasion of micro-organisms or foreign material.
What happens to the B cells of the clone that did not differentiate into plasma cells?
They remain as memory cells.
What do memory cells do?
They spread to all the body tissues to allow the response to occur more rapidly should the antigen enter the body again.
What is Primary Response?
-It is the immune reaction when it is first exposed to an antigen.
Explain how a Primary Response occurs.
- The body’s immune system usually responds fairly slowly, often taking several days to build up large amounts of antibodies.
- It takes times for the B cells to multiply and differentiate into plasma cells.
- As the plasma cells begin to decline.
- However, the primary response leaves the immune system with a memory of that particular antigen.
What is a Secondary Response?
It is a much faster response to the same antigen when it is exposed the second time because of the activity of the memory cells.
Explain how a Secondary Response occurs ?
- Plasma cells are able to form very quickly, with antibody levels in the blood plasma rising rapidly.
- Frequently, this response is so quick that the antigen has little opportunity to exert any noticeable effect on the body and no illness results.
How do antibodies work to provide resistance to infection?
All antibodies combine with the antigen for which they are specific to form an antigen-antibody complex.
List the possible things that the Antibodies may do.
- Combine with foreign enzymes or bacterial toxins, or inactivate them by inhibiting reaction with other cells or compounds.
- Bind to the surface of viruses and prevent the viruses from entering cells.
- Coat bacteria so that the bacteria are more easily consumed by phagocytes.
- Cause particles such as bacteria, viruses or foreign blood cells to clump together - a process known as agglutination.
- Dissolve organisms.
- React with soluble substances to make them insoluble and thus more easily consumed by phagocytes.
What is the function of Cell-mediated immunity?
- It provides resistance to the intracellular phase of bacterial and viral infections.
- It is also important in providing resistance to fungi and parasites, and is involved in the rejection of transplants of foreign tissue.
- It also appears to be important to fighting cancer cells.
What does the pathogens (such as bacteria responsible for tuberculosis and legionnaire’s disease) do?
They specialise in invading and replicating inside their hosts’ own cells, making them particularly difficult to overcome.
What are T lymphocytes?
- They are responsible for cellular immunity.
- They occur in the same lymphoid tissue as the B cells but occupy different areas of the tissue.
- Like the B cells, there are thousands of different types of T cells, and each type responds only to one particular antigen.
Explain the role of the T lymphocytes.
- When a foreign antigen, such as a virus or bacterium, enters the body, the particular type of T cells that are specifically programmed for that antigen become activated or sensitised.
- This only occurs after a B cell or macrophage encounters the foreign antigen, travels to the nearest lymph node and presents it to the T cells.
What happens to the sensitised T cells?
- They enlarge and divide, each giving rise to a clone, a group of identical T cells.
- Some cells of the clone remain in the lymphoid tissue as memory cells, which are able to recognise the original invading antigen.
- If infection with the same antigen should occur again, these memory cells can initiate a much faster response to the second and subsequent infections.
What 3 types of T cells are produced when the T cells do not become memory cells?
- Killer T cells
- Helper T cells
- Suppressor T cells
What are Killer T cells?
- They migrate to the site of infection and deal with the invading antigen.
- They attach to the invading cells and secrete a substance that will destroy the antigen, and then go off in search of more antigens.
What are Helper cells?
They play an important role in both humoral and cellular immunity.
What are the roles of the substances that Helper cells secrete?
- Cause lymphocytes at the infection site to become sensitised, thus intensifying the response.
- Attract macrophages to the place of infection so that the macrophages can destroy the antigens by phagocytosis.
- Intensify the phagocytic activity of macrophages.
What are suppressor T cells?
- They act when the immune activity becomes excessive or the infection has been dealt with successfully.
- They release substances that inhibit T and B cell activity, slowing down the immune response.
SUMMARISE Antibody-mediated immunity. (Humoral Immunity)
- Works against bacteria, toxins and viruses before they enter the body’s cells; also against red blood cells of a different blood group than the person.
1. Foreign antigen reaches lymphoid tissue.
2. Certain B lymphocytes are stimulated to undergo rapid cell division.
3. Most new B cells develop into plasma cells, which produce antibodies and release them into blood and lymph.
4. Antibodies combine with the specific antigen and inactivate or destroy it.
5. Some of the new B cells form memory cells.
SUMMARISE Cell-mediated immunity. (Cellular Immunity)
- Works against transplanted tissues and organs, cancer cells and cells that have been infected by viruses or bacteria; also provides resistance to fungi and parasites.
1. Foreign antigen reaches lymphoid tissue.
2. Certain T lymphocytes are stimulated to undergo rapid cell division.
3. Most new T cells develop into killer T cells or helper T cells, which migrate to the site of the infection.
4. Killer T cells destroy the antigen, while helper T cells promote phagocytosis by macrophages.
5. Some sensitised T cells form memory cells.
What is Immunity ?
It is the resistance to infection by invading micro-organisms.
What is Natural Immunity?
- It occurs without any human intervention; artificial immunity results from giving people an antibody or antigen.
- It can be passive or active.
What is Passive Immunity?
- It is when a person is given antibodies produced by someone else.
- The individual’s body plays no part in the production of antibodies.
- Short-lived: it lasts only until the antibodies are broken down and excreted.
How can Passive Immunity occur?
- This can occur naturally when antibodies from the mother pass across the placenta to a developing foetus or when the mother’s antibodies are passed to the baby in breast milk.
- It can be gained artificially when a person is injected with antibodies to combat a particular infection.
- This is often done when a person is exposed to pathogens that cause serious diseases, such as tetanus, diphtheria and rabies.
Why are Antibodies given?
So that immunity is established immediately.
What is Active Immunity?
- It occurs when the body is exposed to a foreign antigen and manufactures antibodies in response to that antigen.
- This type of immunity is prolonged because, although the amount of the antibody produced gradually decreases, the ‘memory’ of that antigen persists through the memory cells once the antigen has been dealt with.
- Lasts for many years, often for life.
- Active immunity to a disease can result from an actual attack of the disease (natural active immunity) or from an injection of the antigens associated with the disease (artificial active immunity).
Summarise Passive Immunity.
Natural: Antibodies enter the bloodstream across the placenta or in breast milk.
Artificial: Antibodies are injected into the bloodstream.
Summaries Active Immunity.
Natural: Ability to manufacture antibodies results from an attack of a disease.
Artificial: Ability to manufacture antibodies results from being given an antigen by vaccination.
What is the difference between Immunisation and Vaccination?
Immunisation: Programming the immune system so that the body can respond rapidly to infecting micro-organisms.
-It can occur naturally or artificially.
Vaccination: It is the artificial introduction of antigens of pathogenic organisms so that the ability to produce the appropriate antibodies is acquired without the person having to suffer the disease.
Why do people who have had disease such as diphtheria, chickenpox, measles, mumps and poliomyelitis are normally immune to these diseases for the rest of their lives?
-This is due to the natural active immunity.
What is Vaccine?
It is the antigen preparation used in artificial immunisation.
What are the 4 types of traditional vaccines?
- Vaccines containing living attenuated micro-organisms.
- Vaccines containing dead micro-organisms.
- Vaccine made from filtrates of bacterial cultures containing Toxins.
- Sub-unit vaccine.
What are Vaccines containing living attenuated micro-organisms?
- They are micro-organisms of reduced virulence; that is, micro-organisms with a reduced ability to produce disease symptoms, so that the immunised person does not contract the disease but manufactures antibodies against the antigen.
- Vaccines containing living attenuated micro-organisms include those for immunisation against polio, tuberculosis, rubella (German measles), measles, mumps and yellow fever.
When were vaccines containing living attenuated micro-organisms first used?
- Louis Pasteur first used this method to immunise chickens against fowl cholera, and sheep and cattle against anthrax.
- He attenuated the bacteria by exposing them to a temperature of 42C (5C higher than normal body temperature) for about a week.
What are vaccines containing dead micro-organisms?
- Immunity produced in this way is not usually as prolonged as it would be with immunisation using live attenuated micro-organisms.
- Examples: Cholera, typhoid and whooping cough vaccines.
What are vaccines containing toxins?
- Made from filtrates of bacterial cultures.
- In cases where bacteria produce their effects in humans by liberating toxins, it is not necessary to use living or dead bacteria for immunisation.
- The toxins produced by the bacteria can be inactivated, so that when they are injected into someone they do not make the person ill.
- Such inactivated toxins are called toxoids.
- Injections of toxoids are used to immunise against diphtheria and tetanus.
What are Sub-unit vaccines?
- Instead of using a whole dead or attenuated micro-organisms, a fragment of the organism is used to provoke the immune response.
- Sub-unit vaccines are used for vaccination against human papilloma virus (Gardasil) and hepatitis B.
What are some of the problems associated with these effective vaccines?
- Risk of side effects.
- Effective for only a short period.
What are some approaches that has been used to modify the characteristics of the pathogen?
- By slightly changing the DNA in the micro-organism’s cell so that the pathogen is less virulent.
- Insert certain DNA sequences from the pathogen into harmless bacterial cells.
What is the purpose of inserting certain DNA sequences from the pathogen into harmless bacterial cells?
The chosen DNA sequence causes the production of antigens that are characteristic of the pathogen.
List the types of vaccines involved in immunisation against some disease.
- Living attenuated micro-organisms: Measles, mumps, rubella, rabies, poliomyelitis, tuberculosis, yellow fever.
- Dead micro-organisms: Cholera, bubonic plague, typhoid, whooping cough, influenza, hepatits A.
- Toxoids: Diphtheria, tetanus.
- Sub-Unit: Human papilloma virus, hepatitis B.
What is the most common method of vaccination?
It is to inject the vaccine using a syringe but other forms of delivery can be used.
Summarise all the types of Vaccine Delivery researches.
- Given by mouth in a sweet syrup or in lumps of sugar.
- One type of Polio Vaccine
- no longer used in Australia but it is still used in many countries. - Use of a very fine spray into the nostrils.
- Being trialled
- A nasal spray called FluMist is widely used in the United States for protection against the influenza virus. - Skin Patches.
- Self-administered
- Patches could even be sent to people through the post.
- Could be useful in developing countries where medical services are not readily available.
What is another line of research that has been abandoned? and Why?
Vaccines in food.
- Abandoned research because of difficulties in controlling the dose and the vaccine production gene could be passed to other varieties of the food plant.
- Attempts
- Attempts are not being made to engineer non-food plants to produce vaccines.
- People can be given a measured amount of the plant to include in their food.
- Scientists in India have genetically engineered several plants to produce a vaccine for hepatitis B.
What are one of the public health measures that has had the greatest impact on people’s health?
The World Health Organization (WHO) rated the introduction of vaccines as one of them.
What is WHO’s greatest success?
Probably the global elimination of smallpox.
What vaccination program takes place in Australia especially during winter?
Prior to winter each year, the federal government supports a program to vaccinate the young and elderly against the current strains of the influenza virus.
What is herd immunity?
- It depends on a high proportion of individuals being immunised.
- When there are a large number of immune individuals in a populations, there is less chance of the disease being transmitted between them.
What is one problem for health departments in all countries?
- As the incidence of infectious disease declines, people become complacent and may decide that the risk of side effects from the vaccine is higher than the risk of contracting the disease itself.
- If vaccination rates do decline, a serious outbreak of disease may occur.
Why shouldn’t vaccination start too soon after birth?
- Because the child’s blood contains antibodies from its mother.
- If a newborn is given a vaccine, the antibodies from the mother have entered the child’s bloodstream via the placenta or in the breast milk eliminate the foreign materials in the vaccine.
- This occurs before the child’s immune system can mount an immune response.
- A few months are necessary for the child’s immune system to become activated and therefore able to prevent the child from getting the diseases that they are being vaccinated against.
Summaries the Recommended vaccination schedule for Australians.
Birth - Hepatitis B
2 and 4 months - Diphtheria, tetanus, whooping cough (DTP); polio; hepatitis B; Haemophilus influenza type B (HiB); rotavirus*; pneumococcal**
6 months - Diphtheria, tetanus, whooping cough, polio, HiB, rotavirus, pneumococcal, hepatitis B
12 months - Measles, mumps, rubella (MMR), hepatitis B (if not given at 6 months), HiB, meningococcal C***
18 months - Chickenpox
4 years - Diphtheria, tetanus, whooping cough, polio, measles, mumps, rubella.
10-13 years - Hepatitis B, chickenpox
15-17 years - Diphtheria, tetanus, whooping cough
50 years and over - Influenza (annually), pneumococcal (for Aboriginal and Torres Strait Islander people)
65 years and over - same as above.
Is one shot of vaccine enough ?
Unfortunately no.
What happens when a person is vaccinated?
- His or her immune system will active a certain number of B cells.
- These cells will multiply and some will produce antibodies.
- Others will become memory cells.
Summaries the Recommended vaccination schedule for Australians.
Birth - Hepatitis B
2 and 4 months - Diphtheria, tetanus, whooping cough (DTP); polio; hepatitis B; Haemophilus influenza type B (HiB); rotavirus*; pneumococcal**
6 months - Diphtheria, tetanus, whooping cough, polio, HiB, rotavirus, pneumococcal, hepatitis B
12 months - Measles, mumps, rubella (MMR), hepatitis B (if not given at 6 months), HiB, meningococcal C***
18 months - Chickenpox
4 years - Diphtheria, tetanus, whooping cough, polio, measles, mumps, rubella.
10-13 years - Hepatitis B, chickenpox
15-17 years - Diphtheria, tetanus, whooping cough
50 years and over - Influenza (annually), pneumococcal (for Aboriginal and Torres Strait Islander people)
65 years and over - same as above.
Is one shot of vaccine enough ?
Unfortunately no.
What happens when a person is vaccinated?
- His or her immune system will active a certain number of B cells.
- These cells will multiply and some will produce antibodies.
- Others will become memory cells.
What is so cool about Memory Cells?
Memory cells can last for decades in a person’s body and are able to produce the necessary antibody when exposure to the micro-organism occurs again.
What are booster shots?
- In most cases, the first dose of a vaccine does not enable enough B cells to become activated.
- Booster shots are required to activate more B cells.
- When more B cells are activated more antibodies are made.
- This in turn results in greater protection from the disease-causing micro-organism that the person was vaccinated against.
What is one of the main risk of vaccination ?
- An allergic reaction.
- This may occur not so much from the vaccine itself but from a reaction to the medium in which the vaccine was cultured.
eg. many influenza vaccines are manufactured in fertilised eggs and people who are allergic to egg protein need to be aware of this. Similarly, people who are allergic to yeast would need to be mindful that some of the older Hepatitis B vaccines have this as a component.
What is another concern that has been expressed regarding vaccine?
- It is impossible to completely isolate one virus from others within an animal tissue that is being used as a culture medium.
- As a result, vaccines could pose a risk of cross-species disease introduction.
What preservatives are included in vaccines?
- formaldehyde
- phenol (carbolic acid)
- aluminium
- phosphate, alum and acetone
What are some concerns of preservatives in vaccines?
- Individuals concerned about vaccination claim that these preservatives are able to affect the nervous system and can lead to other health issues.
- Frequently, studies following such claims have indicated that the association is due to chance alone.
What are the major ethical concerns?
- Use of vaccines centre around how the vaccine was manufactured.
- How it was tested
- Risks associated with its use
What are the specific ethical concerns?
- The use of human tissue.
- The trialling of vaccines in developing countries.
- Experimentation on animals.
- Discontinuing the testing of vaccines on animals would benefit
- Risks that parents have to take into consideration when making decisions on vaccination for their child.
- Some vaccines are most effective with girls who have yet to become sexually active (11-12yrs old) some say this age is too young.
What are antibiotics?
-Antibiotics are drugs that are used to fight infections of micro-organisms, particularly bacteria.
State a Fun fact about antibiotics.
Before antibiotics came to be widely used in the 1940s, a person could die from an infected cut or scratch that today would be considered a minor problem.
What are the 2 types of antibiotics ?
- Bactericidal Antibiotics - kill bacteria by changing the structure of the cell wall or cell membrane, or by disrupting the action of essential enzymes.
- Bacteriostatic Antibiotics - Stop bacteria from reproducing, usually by disrupting protein synthesis.
Both types are effective in treating bacterial infections.
What’s the difference between broad spectrum antibiotics and narrow spectrum antibiotics?
Broad - affect a wide range of different types of bacteria.
Narrow - effective only against specific types of bacteria.s
What is a multiple drug resistance bacteria?
- Also referred to as ‘super bugs’.
- It is where some strains of bacteria are resistant to most or all of the available types of antibiotics.
What are antiviral drugs?
- As the name suggests, antiviral drugs are used specifically for treating viral infections.
- Unlike most of the antibiotics that destroy pathogenic bacteria, antivirals inhibit the development of the virus.
