15 Flashcards
What is hypersensitivity?
Hypersensitivity means your immune system reacts too strongly to something that shouldn’t cause harm.
What causes hypersensitivity?
Past exposure: The immune system has ‘seen’ the thing before, remembers it, and now reacts very strongly.
What is sensitization?
Your body is trained to react after the first exposure.
What are the three main causes of hypersensitivity reactions?
- Self-antigens (Autoimmunity)
- Microbes (Germs)
- Harmless environmental things (Allergens)
What is an example of self-antigen hypersensitivity?
Type 1 diabetes.
What is an example of hypersensitivity due to microbes?
Rheumatic fever after a strep infection.
What is an example of allergen hypersensitivity?
Peanut allergy.
What is Type I hypersensitivity?
Immediate (IgE-Mediated) Hypersensitivity.
What happens during Type I hypersensitivity?
First exposure creates IgE antibodies that attach to mast cells, leading to degranulation upon re-exposure.
What is the timeline for Type I hypersensitivity reactions?
Happens within minutes.
What are some symptoms of Type I hypersensitivity?
- Runny nose
- Sneezing
- Swelling
- Itchy eyes
- Hives
- Anaphylaxis (in serious cases)
What are some examples of Type I hypersensitivity?
- Hay fever
- Food allergies (peanuts, shellfish)
- Asthma
- Eczema
What is Type II hypersensitivity?
Antibody-Mediated (Cytotoxic) Hypersensitivity.
What happens during Type II hypersensitivity?
Body makes IgG or IgM antibodies against its own cells, leading to destruction, inflammation, and messed up signals.
What is the timeline for Type II hypersensitivity reactions?
Within hours to a day.
What are some examples of Type II hypersensitivity?
- Blood transfusion mismatch
- Myasthenia gravis
- Grave’s disease
- Pernicious anemia
What is Type III hypersensitivity?
Immune Complex-Mediated Hypersensitivity.
What occurs during Type III hypersensitivity?
Antibodies bind to antigens, forming immune complexes that get stuck in tissues and cause inflammation.
What is the timeline for Type III hypersensitivity reactions?
6–10 days after exposure.
What are some examples of Type III hypersensitivity?
- Lupus (SLE)
- Post-strep glomerulonephritis
- Serum sickness
- Arthus reaction
What is Type IV hypersensitivity?
Delayed-Type (T Cell-Mediated) Hypersensitivity.
What happens during Type IV hypersensitivity?
T cells recognize antigens and either release cytokines causing inflammation or directly kill body cells.
What is the timeline for Type IV hypersensitivity reactions?
Delayed – happens 1 to 3 days later.
