Biology
Home > Biology > Core > The search for better health > Search for better health: 5. The immune response
9.4 Search for better health: 5. The immune
response
| Syllabus reference (October 2002 version) | ||
|---|---|---|
5. MacFarlane Burnet's
work in the middle of the twentieth century contributed
to a better understanding of the immune response and
the effectiveness of immunisation programs
|
Students learn to:
|
Students learn to: |
Extract from Biology Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW
Background
Sir Frank Macfarlane Burnet was an Australian scientist who won the Nobel Prize for his research into physiology. He studied immunology and worked on the development of the influenza vaccine.
Burnet, Frank Macfarlane (1899 - 1985) 
University of Melbourne
identify
components of the immune response
- antibodies
- T cells
- B cells
| Name
|
What it is
|
What it does
|
|---|---|---|
| antibodies
|
proteins that the body produces when it
detects antigens. Each different antigen stimulates the
production of its own particular antibody.
|
join with antigens so that they are
clumped together and can be more easily recognised and
destroyed by macrophages
|
| B cell
|
a special kind of lymphocyte produced in
the bone marrow (thus B cell)
|
When a B cell recognises an antigen, it
divides repeatedly to produce a mass of identical cells
(clones) that work as antibody producers
(plasma cells).
|
| T cell
|
another kind of lymphocyte, that is passed
through the thymus gland (thus T cell)
|
Some produce toxic substances that destroy
cells that have been invaded by a virus. Others help
the B cells to divide rapidly.
|
describe and explain the immune response in the human body in terms of:
- interaction between B and T lymphocytes
- the mechanisms that allow interaction between B and T lymphocytes
- the range of T lymphocytes types and the difference in their roles
Interaction between B and T lymphocytes
B and T lymphocytes interact as they are both attacking the
same antigen. Helper T cells (see below) stimulate B cells and
T cells to clone.
The mechanisms that allow interaction between B and T
lymphocytes
The T lymphocytes that help B lymphocytes are called helper
T cells (Th cells). If a B cell has an antigen
on its surface, there is a risk that a T cell will recognise
the antigen and attack it together with the B cell. This does
not happen because T cells are able to recognise
“self” molecules that are on the surface of B
cells. Every person has their own particular "self"
molecules, so there are millions of different B cells. They are
like personal identity used to identify cells to T lymphocytes.
This means that, in the case of organ transplants, T cells can
recognise cells that have come from a different body and so
help B cells to destroy them. Only identical twins have the
same “self” molecules on their B cells.
The range of T lymphocytes types and the difference in
their roles
| Type of T cell
|
Roles
|
|---|---|
| killer T cells (Tc cells)
|
attack and destroy macrophages that have
engulfed an antigen. They produce cytotoxins.
|
| helper T cells (Th cells)
|
secrete chemicals that stimulate cloning
in B and T cells
|
| memory T cells
|
remain in the body and reactivate quickly
with subsequent infections by the same antigen
|
| suppressor T cells
|
stop the reaction when the antigen is
destroyed
|
Antibody production Cells alive
outline the reasons for the suppression of the immune response in organ transplant patients
- When an organ is transplanted it is recognised by the immune system in the body as non-self. The body attacks the new organ as if it is an invading pathogen. To overcome this problem, transplant patients are given powerful drugs to suppress their natural defences. This can lead to complications, as the patient has reduced defences against any pathogen that they may encounter.
process, analyse and
present
information from secondary sources to evaluate the
effectiveness of vaccination programs in preventing the
spread and occurrence of once common diseases, including
small pox, diphtheria and polio
Background
Vaccination gives artificially acquired immunity from a
disease. Once common diseases, such as small pox, diphtheria
and polio, are now uncommon because of successful vaccination
programs. Smallpox was the first disease for which a vaccine
was developed. Edward Jenner did this in 1796. The
vaccination program that was started in the 1960s was so
successful that the World Health Organisation (WHO) has
declared it eradicated. Diphtheria vaccine is given as part
of a triple antigen injection that protects against
diphtheria, tetanus and whooping cough. In 1990, WHO stated
that 80% of children had been vaccinated against this
disease. There continues to be outbreaks of this disease and
continued vaccination is recommended. It is no longer thought
of as a major child killer. Polio caused thousands of
children to become paralysed every year. A vaccine was
introduced in 1955. It became available as an oral vaccine in
the 1960s. Worldwide, the number of cases is down by 80%.
- Use the Internet, biology text books and encyclopedias to gather information on the use of vaccines over the last 200 years and on the use of vaccines in controlling common diseases. Make sure you gather information on small pox, diphtheria and polio. Numerical data or graphs are particularly useful for the evaluation purposes.
- Assess the reliability of secondary information and data by considering information from various sources. This is an ideal opportunity to process claims about the effectiveness of vaccination made in the mass media.
- Analyse information by identifying trends or contradictions.
-
Present your findings as an evaluation
report. Consider such aspects as how vaccination programs
are implemented in Australia and different parts of the
world. Discuss the problems associated with producing and
using vaccines, especially in less developed countries.
Comment on the effectiveness of vaccination. Consider using
graphs to demonstrate the points you make.
Immunisation
Academy of Science
Smallpox Academy of Science
Diptheria World Health Organisation
Polio World Health Organisation
Centenary Article: Child health since Federation
Professor Fiona J Stanley, Year Book Australia, 2001. Reproduced on the Australian Bureau of Statistics web site.
outline the
way in which vaccinations prevent infection
Background
When a person has had an infection, some of the B cells
produced in response to the pathogen are stored in the
lymphatic tissue. They are called memory B cells.
They are ready to provide a very rapid response if the same
pathogen later attacks the body.
- Vaccination is a way of giving a person the “experience” of having had an infection without actually having it, so that the body responds to the “experience” by producing the appropriate memory B cells.
- The way in which the “experience” is given depends on the pathogen. In the case of small pox a very similar, but very much less harmful pathogen (cow pox), was used. In other cases, the virus is made weaker, and therefore harmless (attenuated), before being used in a vaccine. Examples of this type of vaccine are those for poliomyelitis, measles and whooping cough.
- Many pathogenic bacteria are harmful to the body because of the toxins they produce. For diphtheria these toxins are modified to produce the vaccine.
- Whatever the source of the vaccine, the effect is the same. It introduces antigens into the body so that B cells are activated to produce large amounts of antibody and B cells that are stored in the lymph system are ready for a future attack by the particular pathogen.
|