Download Name ______ Class __________ Date _____________ Immune

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Immune Problems
A strong immune system works so well and so quietly that we often don’t realize how many
times it has saved our lives. However, some people have a deficiency in their immune system where
something is missing or does not work properly. When the immune system does not function
properly, the body is unable to fight infections that would not usually be a problem to fight. Immune
deficiencies can be inherited, acquired through infection, or produced as an unintended side effect of
a drug. They can affect antibodies, T-cells and B cells (cells that help you fight infection), and other
substances normally produced by the immune system.
Sometimes there is a medical reason for suppressing the immune system. For example, after
having an organ transplant, a person is given drugs that suppress (stop) immune function. Because
the body does not recognize the transplanted organ, it will label it as an antigen and attack, just as if
you were given the wrong blood type. These drugs are needed to keep the immune system from
attacking the organ. An organ transplant recipient will need to take immunosuppressant drugs for the
rest of their lives.
Another immunity problem is someone who suffers from allergies. Allergies are an immune
response to an antigen that is not harmful to the body (ex: pollen, mold or proteins found in some
food). The body’s response is to release histamines, which causes inflammation. To some people
these allergic reactions are extremely dangerous. Bee stings, certain foods and some medications
can cause swelling in areas of the body (throat, tongue, etc.) that can block airflow and lead to death.
AIDS (Acquired Immune Deficiency Syndrome) is a well known problem with the immune
system. It is caused by HIV (Human Immunodeficiency Virus) which is a viral disease that damages
the immune system leaving it unable to fight infections and cancerous cells. People who have AIDS
are very susceptible or vulnerable to other infections because their immune systems no longer work
properly. HIV is transferred between humans through the direct contact of body fluids such as blood,
semen, and breast milk. It is NOT transmitted through sitting on a toilet seat, shaking hands or other
forms of casual contact. Mosquitoes and ticks do not transmit HIV. Remember HIV is a virus; it
depends on the body’s cells to be able to replicate itself. Once this virus has entered your body, it
destroys your immune system and its ability to fight infection. There is currently no vaccine or cure for
HIV. Once infected, the prognosis is death. However some drugs can slow the progression from HIV
to AIDS, allowing a person to live longer than expected.
Any disruption within the human body causes an imbalance, which affects the homeostasis of
that organism. Disruptions in the immune system are extremely bad because they can lead to death.
Copy and answer the following questions.
1. Explain how your body rejecting a transplanted organ is similar to an immune response when
receiving the wrong blood type.
2. Explain how allergies are an immune response.
3. Why are people with HIV more likely to contract other infectious diseases?
Regents Practice:
Base your answer to the questions on the information below and on your knowledge of biology.
An Experimental SARS Vaccine Works in Animals
Scientists reported that they had protected animals from the effects of the SARS virus by using an
experimental vaccine. The SARS virus causes an acute respiratory illness in humans and other animals.
This vaccine was sprayed once into the nostrils of each of four African green monkeys. Four weeks later,
these monkeys were exposed to the virus that causes SARS. The monkeys showed no sign of the
disease in their respiratory tracts. Blood tests confirmed the presence of proteins known as neutralizing
antibodies that indicate protection against disease. The scientists also sprayed a placebo (a substance
that did not contain the vaccine) into the nostrils of each of four other African green monkeys. After
exposure to the virus that causes SARS, all of these monkeys developed symptoms of this condition.
Briefly explain the nature of a vaccine and some steps that should be taken before a vaccine is available
for public use. In your answer, be sure to include:
• a description of what a vaccine is [1]
• an explanation of why one group had a placebo sprayed into their nostrils before exposure to the virus
[1]
• an explanation of why scientists used monkeys to test the SARS vaccine [1]
• a statement of what could be done to verify the results [1]
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