Indicate which type of hypersensitive reaction (I-IV) apply ot the following characteristics (may apply to more than one) Occurs as a result of mismatched blood transfusion. (ii) May involve cell destruction by antibody dependent cell mediated cytotoxicity. (iii) Localized form characterized by wheel-and-flare reaction. (iv) Is an important defense against intracellular pathogens. (v) Drug-induced haemolytic anemia.

SouravSeptember 4, 2024

Answer

Here’s how each characteristic corresponds to the different types of hypersensitivity reactions:

Type I Hypersensitivity (Immediate/Anaphylactic Reactions)

• (iii) Localized form characterized by wheel-and-flare reaction: This describes typical allergic reactions, such as those seen in insect stings or certain allergens, resulting in immediate hypersensitivity reactions.

Type II Hypersensitivity (Antibody-Mediated Cytotoxic Reactions)

• (i) Occurs as a result of mismatched blood transfusion: Mismatched blood transfusion can lead to Type II hypersensitivity, where antibodies against blood group antigens cause hemolysis of the transfused red blood cells.
• (ii) May involve cell destruction by antibody-dependent cell-mediated cytotoxicity (ADCC): In this reaction, antibodies bind to target cells, and immune cells with Fc receptors (e.g., NK cells) destroy the target cells.
• (v) Drug-induced hemolytic anemia: Certain drugs can induce antibodies that target red blood cells, leading to their destruction in Type II hypersensitivity.

Type III Hypersensitivity (Immune Complex-Mediated Reactions)

• (iv) Is an important defense against intracellular pathogens: Type III hypersensitivity involves immune complexes (antigen-antibody complexes) and is crucial in responses to some infections, though it is also associated with immune complex diseases like lupus and rheumatoid arthritis. This type can be associated with defense against intracellular pathogens indirectly, through immune complex formation.

Type IV Hypersensitivity (Delayed-Type Hypersensitivity)

• This type does not specifically apply to the characteristics listed, but it is important to note that it involves T cell-mediated responses and can lead to chronic inflammation and tissue damage over time.

Summary

• Type I: (iii) Localized form characterized by wheel-and-flare reaction.
• Type II: (i) Mismatched blood transfusion; (ii) Cell destruction by ADCC; (v) Drug-induced hemolytic anemia.
• Type III: (iv) Important in defense against intracellular pathogens (indirectly related).