Question

"Wheal and Flare" reaction is characteristic reaction associated with identification of:

• A. Type-1 hypersensitivity reaction
• B. Type-2 hypersensitivity reaction
• C. Type-3 hypersensitivity reaction
• D. Type-4 hypersensitivity reaction

Answer 1

The Correct Option is A

The question is about identifying the hypersensitivity reaction associated with the "wheal and flare" response. Let's explore each option to determine the correct match:

Understanding Hypersensitivity Reactions

1. Type-1 Hypersensitivity Reaction
   • This reaction is also known as an immediate hypersensitivity reaction.
   • It is mediated by IgE antibodies.
   • The classic example of a Type-1 hypersensitivity reaction is an allergic reaction, such as hay fever, asthma, or anaphylaxis.
   • The response includes a rapid onset of symptoms, typically within minutes of exposure to the antigen.
   • Characteristic Features: The key feature here is the "wheal and flare" reaction, which is a skin response that includes edema (wheal) and redness (flare).
2. Type-2 Hypersensitivity Reaction
   • This involves IgG or IgM antibodies targeting antigens on cell surfaces or the extracellular matrix.
   • Examples include hemolytic anemia and Goodpasture's syndrome.
   • It does not exhibit a wheal and flare reaction, rather it causes cell destruction, inflammation, or altering cellular function.
3. Type-3 Hypersensitivity Reaction
   • This involves immune complex-mediated reactions.
   • Diseases like systemic lupus erythematosus (SLE) and rheumatoid arthritis are examples of Type-3 reactions.
   • This reaction typically presents with systemic inflammation rather than local wheal and flare.
4. Type-4 Hypersensitivity Reaction
   • This is a delayed-type reaction mediated by T-cells rather than antibodies.
   • Examples include contact dermatitis and the Mantoux test for tuberculosis.
   • This reaction does not involve a wheal and flare response.

Conclusion

The "wheal and flare" reaction is specifically associated with a Type-1 hypersensitivity reaction. The appearance of a wheal, which is a raised area, and a flare, which is redness around it, is due to the vasodilation and increased vascular permeability caused by histamine release from mast cells in an allergic response.

Therefore, the correct answer is: Type-1 hypersensitivity reaction.