Chap 19 Flashcards
Define hypersensitivity
Also called allergy; enhanced immune reaction leading to pathological changes.
Antigenic response that results in undesirable effects
Hypersensitivity
When does hypersensitivity happen?
People who have been sensitized by previous exposure to an antigen
Allergen
Antigen that causes hypersensitivity
During hypersensitivity, what happens when a sensitized individual is exposed to the antigen again?
The body’s immune system reacts to it in a damaging manner
Immunopathology
The study of hypersensitivity reactions
The study of hypersensitivity reactions is called
Immunopathology
What are the four principal types of hypersensitivity reactions?
1.Anaphylactic
2.cytoxic
3. Immune complex
4. Cell-mediated
Delayed-type reactions
Cell-mediated
A reaction that occurs in a sensitized individual resulting in tissue damage, rather than immunity
Hypersensitivity reaction
Reactions that happen 2-30 minutes after a sensitized person is exposed to an antigen
Type I Anaphylactic reactions
Anaphylaxis in Greek means
Opposite of protected
Anaphylaxis
A hypersensitivity reaction involving IgE antibodies, last cells and basophils
Systemic anaphylaxis reactions can lead to
Shock, breathing difficulties, sometimes fatal
Localized anaphylaxis reactions can lead to
Common allergic conditions such as hay fever, asthma and hives
Are all immune responses beneficial?
No, too strong reactions can be life threatening
Mast cells are especially prevalent in
1.The mucosal and connective tissue of skin
2.respiratory tract and surrounding blood vessels
Basophils in the bloodstream are recruited to
Site of infection.
Mast cells and basophils contain
Granules of histamine and other chemical mediators
What type of cells do IgE antibodies bind to?
Mast cells and basophils
Which are the steps of an anaphylactic reaction?
- IgE binds to mast cells and basophils
- Antigen molecules cross-link adjacent IgE molecules
- Degranulation occurs
- Chemical mediators such as histamine are released
- Capillary permeability and smooth muscle contractions increase
- Neutrophils and eosinophils move to the site
Which is true regarding systemic anaphylaxis?
1.Systemic reaction can be fatal in only a few minutes
2. Result in dramatic decrease in blood pressure
3. Commonly associated with injected antigens
What are the outcomes of taking antihistamine?
- Decreased mucus
- Decreased histamine-based stimulation of cells
- Decreased permeability of blood vessels
What is the purpose of desensitization programs?
Repeated exposure to the (wasp venom) antigen will increase the amount of IgG made by the immune system
Desensitization can be accomplished by injecting small amounts of
The antigen/allergen
Helps prevent allergic response
Desensitization
The IgG molecules made during desensitization function as
Blocking antibodies
Blocking antibodies are extremely effective in
Providing protection from a hypersensitivity reaction
Why are blocking IgG antibodies so effective at protecting from another response to wasp venom?
The blocking IgG antibodies outnumber the IgE antibodies and bind to wasp venom before the IgE antibodies can bind
HIV induces AIDS by
Killing helper T cells, reducing the number of cells below 200 per microliter
Which HIV diagnostic method tests for HIV directly?
PCR, used to determine if HIV RNA is present in patient samples
HIV is spread by
-Blood,
-Breast milk
-Unprotected sexual intercourse
HIV infects which cells?
Immune cells
CD4-positive T-helper cells and macrophages. Does not infect cells of the digestive system or lungs.
Which group of anti retroviral drugs prevents viral assembly and release?
Protease inhibitors
Protease inhibitors
Prevent large viral proteins from cleaving into smaller, viral proteins
Protease inhibitors help prevent
Viral assembly and release from infected cells
Progress of HIV infection in adults can be divided into 3 steps
- Infection is asymptomatic. HIV population in blood is at its highest
- CD4+ T cells undergoes steady decline, but few serious symptoms are apparent
- Clinical AIDS. CD4+ T cells counts drop below 200 cells per microliter
Type 1 hypersensitivity results from
Release of inflammatory molecules in response to an antigen
Type 2 hypersensitivity results when
Cells are destroyed by the immune system
Type 3 hypersensitivity results when
Antigen antibody complexes become trapped in organs, including the joints and blood vessels
Proteins made by wbcs that adhere to complementary antigens on the surface of rbcs
Antibodies
Passive immunotherapy
Delivery of pathogen specific antibodies to an individual
The antibodies in passive immunotherapy immediately
Bind to the pathogen specific antigens, ultimately leading to the elimination of the pathogen
Active immunotherapy
Immunization.
Delivery of pathogen specific antigens to a person. Adaptive immune response is generated. In a week, antigen specific antibodies will be produced and will ultimately lead to the elimination of the pathogen
Passive immunotherapy does not make
Memory cells, protection is temporary
Live vaccines
Contain attenuated pathogens
Killed vaccines
Pathogens unable to replicate
Toxoid vaccines
Uses modified toxins
Combination vaccine
Contains antigens from multiple pathogens
Live vaccines contain
Avirulent microbes
Capable of replicating
Which are the possible complications of vaccination?
-residual virulence
-anaphylactic shock
-fever/seizures
