Patho 4 Quiz 2026 | Immune Disorders &
Hypersensitivity Reactions | Practice
Questions & Verified Answers
Ch 12 – Immune Disorders
1. List and describe the 4 types of hypersensitivity reactions. Define anaphylaxis
and identify treatments.
Hypersensitivity reactions are exaggerated or inappropriate immune responses that cause tissue
damage. Too much immune reaction
Type I-III are antibody mediated|
• Type I (IgE-mediated): ALLERGIES; This is an immediate allergic reaction where an
allergen triggers IgE antibodies bound to mast cells and basophils, leading to the release
of histamine and other inflammatory mediators. It causes symptoms like itching,
swelling, bronchoconstriction, and hypotension. Common examples include seasonal
allergies, asthma, and anaphylaxis
• H1 receptor- responsible for symptom like itching and swelling
• H2 receptors- repsontsible for GI symptoms
- Always a part of adaptive immune response – IgE binds to surface of mast
cells and basophils releasing histamine and symptoms of allergic reaction
- Treatment: antihistamines – block H1 receptors, corticosteroids, Epinephrine
(only for anaphylaxis)
• Anaphylaxis is a life-threatening systemic Type I hypersensitivity reaction. It involves
widespread vasodilation, bronchospasm, and shock. First-line treatment is epinephrine,
followed by airway management, antihistamines, corticosteroids, and IV fluids.
• Type II (Antibody-mediated cytotoxic): TISSUE SPECIFIC; In this reaction, IgG or
IgM antibodies target antigens on cell surfaces, causing destruction through complement
activation or phagocytosis. This occurs in conditions like hemolytic anemia, Myasthenia
Gravis disease, Graves' disease, and blood transfusion reactions autoimmune attacking
Example: Myasthenia Gravis is the autoimmune motor disorder from Ch.12 that IgG antibodies
mistakenly bind/attack acetylcholine receptors leading to muscle weakness.
,• Type III (Immune complex-mediated): Antigen-antibody complexes form and deposit
in tissues (versus reacting on cell surfaces), activating complement and triggering
, inflammation. This leads to diseases like glomerulonephritis, systemic lupus
erythematosus (SLE) and serum sickness.
Only type 4 is T-CELL MEDIATED
• Type IV (T-cell-mediated delayed): This type does not involve antibodies. Instead,
sensitized T cells recognize antigens and release cytokines that cause inflammation,
recruit and activate phagocytosis. It typically develops over 48–72 hours. Examples
include contact dermatitis and the TB skin test.
Differentiate direct cell-mediated cytotoxicity from delayed-type hypersensitivity.
Cell mediated cytotoxicity involves CD8 T cells that directly kill infected abnormal cells
Delayed type hypersensitivity: delayed 24-72hrs involve the CD4 helper T cells release
cytokines that brings in cytokines for phagocytosis/inflammation
2. Define immunodeficiency and distinguish between primary and secondary
immunodeficiency.