Question

A patient received a new heart transplant, but shows signs of graft rejection after 2 weeks. Which type of hypersensitivity reaction is in progress?"

a) Type I
b) Type II
c) Type III
d) Type IV
Please explain why it wouldnt be the other choices

Answer 1

The answer is d) Type IV.

Hypersensitivity reactions are undesirable reactions of an immune system. There are 4 types of hypersensitivity reactions with different response times:
- Type I: Anaphylactic - The response time is few minutes up to 30 minutes.
- Type II: Cytotoxic - The response time is up to few hours.
- Type III: Immune Complex - The response time is 3-8 hours.
- Type IV: Delayed-type - The response time is 2-3 days or more.
Since all types except Type IV have a short response time, it can be concluded that graft rejection after 2 weeks could belong only to Type IV of hypersensitivity.