Immune system: 4 types of reactions Flashcards
Four mechanisms of hypersensitivity
Type 1-4
Type 1 Hypersensitivity
IgE Mediated Reaction, anaphylactoid sensitivity, allergies
What happens during a type 1 reaction?
First exposure
- Exposure to allergen
- Large amount of IgE antibody
- IgE antibodies attach to mast cells
What happens during a type 1 reaction?
Next exposure
- Release of chemical mediators from mast cell (ex: histamine)
- Allergic reaction
- Systemic effects, inflammatory
Symptoms of type 1 reaction
Laryngeal edema
Hypotension
Gastrointestinal cramps and malabsorption
Rhinitis (inflammation of mucus membrane inside nose)
Itching
Dysrhythmias
Type II reaction
Tissue-specific Hypersensitivity
Tissue-specific hypersensitivity
Immune system recognized self antigens as foreign and attacks them
(specific to one type of cell or tissue)
What are the ways that a cell could be destroyed during a type II reaction?
- Complement (protein) destroys cell after antibody bound to a target cell attaches a compliment
- Phagocytosis occurs when the macrophage recognizes and binds the antibody
- Cytotoxic (NK or neutrophils) cells release toxic substances that destroy the cell
- Causes malfunction of cell by blockage f receptors
Type III Reaction
Immune complex mediated reactions
Immune complex mediated reactions
-Immune complexes are formed in circulation and then bind to vessel walls of extravascular tissue
In immune complex mediated reactions, do antigens and antibodies bind cell surfaces?
No they bind to each other
Are type III reaction organ specific?
No!
What do the immune complexes do?
Trigger complement system and attract neutrophils
What are the consequences of immune complexes and attraction of neutrophils?
- Unable to digest
- Lysosomal enzymes are released during the process causing tissue damage
Examples of type III reactions
Serum sickness
Raynaud phenomenon
