Download Chapter 19 Disorders of the Immune System

Chapter 19
Disorders of the immune system
How the virus evades the immune
system
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Damages the cell that plays a central role
High mutation rate
Many strains of the virus are developed.
Antibodies that are produced against one
strain are not effective against the other
strains.
• Stay as provirus – hides from the immune
system
• Stay within the vesicles in the host cell.
• Stimulated the infected cell to fuse with the
infected cell.
• Virus is hopping from one host cell to
another.
• Immune cannot see the virus.
• Indirect ELISA is one of the tests used to
diagnose HIV infection.
• Transmitted by sexual contact, blood
transfusion.
• Contaminated needles
• One of the drugs used to treat the disease
zidovudine
HIV infection
• Divided into 3 categories.
• Category A – no severe symptoms,
swollen lymph nodes.
• Category B – persistent infection by
Candida albicans, diarrhea, fever
• Category C – AIDS ( acquired
immunodeficiency syndrome)
• Candida infection of the esophagus,
tubeculosis, pneumonia.
Hypersensitivity, allergy,
anaphylaxis
• Abnormal immune response
• IgE antibodies are produced against
antigens – pollen, insect venom, fungal
spores.
• First exposure – the person becomes
sensitized.
• Subsequent exposure results in
anaphylaxis.
• Secondary response is stronger.
• Antigen binds to IgE antibodies on the
mast cells.
• Large amount of chemical mediators such
as histamine.
• This leads to allergic reaction
(anaphylaxis).
• Symptoms show up within a few minutes
after the exposure to the antigen.
• Systemic anaphylaxis – caused by
injected antigens such as insect venom.
For example, some people are allergic to
bee sting.
• The venom binds to IgE present on the
surface of mast cells and basophils
stimulate them to release a large amount
of chemical mediators.
• Cause damage to the blood vessel – drop
in blood pressure known as shock.
• Treated with epinephrine.
• Localized anaphylaxis caused by inhaled
antigens such as pollen and fungal spores.
• Mast cells lining the respiratory tract
release histamine.
• Watery eyes, runny nose, coughing and
sneezing.
• Antihistamine.
Allergic contact dermatitis
• T cells are involved
• Reaction to poison ivy is an example.
• First exposure – might not be any
symptoms.
• Subsequent exposure – response is
stronger. Large amount of cytokines are
produced.
• They cause damage to the cells, which
results in rash.
Autoimmune disorders
• Myasthenia gravis – antibodies are
produced against one’s own muscles.
• Death due to respiratory failure.
• Suppressor cells are not working right.
• Antibodies are made against one’s own
cells.