Diseases of the Immune System (8.2) Flashcards
Describe hypersensitivity reactions
Immune system reacts to antigens that pose no threat to the body causing cell damage and disease
Describe the 4 major classifications of hypersensitivity reactions
- type I
- type II
- type III
- type IV
Describe the form of type I hypersensitivity
Immediate
Describe the form of type II hypersensitivity
Cytotoxic
Describe the form of type III hypersensitivity
Immune complex
Describe the form of type IV hypersensitivity
Delayed-type
Provide an alternative term to describe type I hypersensitivity
Allergy
Describe allergy
Rapid and vigorous overreaction of the immune system to allergens
State the 3 hypersensitivity reaction types that can result in autoimmune diseases
- type II
- type III
- type IV
State the 1 hypersensitivity reaction type that can result in allergies
- type I
Describe the type I hypersensitivity reactions
Rapid and vigorous overreaction of the immune system to antigens that are normally harmless
State what the antigens that result in type I hypersensitivity reactions are referred to as
Allergens
State 3 example of typical allergic substances
- pollen
- latex
- peanuts
- MSG
- lobster
State the most extreme type of hypersensitivity type I reaction
Anaphylaxis
State what substance’s release is central to the immediate hypersensitivity reaction
Histamine
State what cells release histamine when encountering the allergen
Mast cells
State what allergic reaction are mediated by
IgE antibody
State what IgE is produced by
Plasma cells
State through what IgE travels through in the body
Bloodstream
State what occurs when the IgE antibody comes into contact with mast cells
Tail end of IgE antibody bind to receptors on cell surface
State what occurs with subsequent exposure to the same allergen
Allergen binds to a pair of adjacent IgE molecules through cross linking
State what the binding via cross linking of IgE antibody to mast cells triggers
Signal transduction cascade that causes mast cells to release histamine
State from what mast cells release histamine
Intracellular vesicles
State by what process mast cells release histamine
Exocytosis
Describe antihistamine
Drug that counteracts the effects of histamine by blocking histamine receptors and suppressing allergic reaction symptoms
State 5 effects of histamine
- blood vessel dilation
- blood pressure decrease
- increase in permeability of blood vessels to immune cells
- contraction of smooth muscles lining airways (making it more difficult to breath)
- activation of fluid-secreting cells (runny nose/tears/sneezing which expels foreign antigens)
State the 2 types of antibodies which are involved in the cytotoxic hypersensitivity reaction
- IgM
2. IgG
State how long it may take for cytotoxic hypersensitivity reactions to occur
Hours
Provide 2 examples of cytotoxic hypersensitivity reactions in humans
- Haemolytic anaemia - mother produces antibodies directed against Rhesus antigens on foetal red blood cells
- Binding of penicillin to red blood cells - if anti-penicillin antibodies are present they may bind to the drug and trigger the destruction of red blood cells
State the 2 types of antibodies which are involved in immune complex hypersensitivity reaction
- IgM
2. IgG
State to what the antibodies in type III hypersensitivity reactions are directed against
Soluble antigens
State what forms when antibodies bind to soluble antigens
Antigen-antibody immune complexes
State where antigen-antibody immune complexes can be deposited
Tissues
State what antigen-antibody immune complexes cause when deposited in tissues
Inflammation
State how long it may take for immune complex hypersensitivity reactions to occur
Hours/days
Provide 1 example of immune complex hypersensitivity reactions in humans
- serum sickness - immune complexes form as a result of a person’s antibodies binding to a foreign antigen in serum
State whether or not delayed-type hypersensitivity reactions are mediated by antibodies
No
State what delayed-type hypersensitivity reactions are mediated by
Helper T lymphocytes
State what helper T lymphocytes activate to produce an immune response
- macrophages
- eosinophil
- cytotoxic T lymphocytes