A small amount of antigen is injected under the skin of a patient. After 30 minutes there is no apparent change at the injection site, but 36 hours later the patient reports that the area is red and swollen. This type of response is due to
A) type II hypersensitivity.
B) immunodeficiency.
C) type I hypersensitivity.
D) type IV hypersensitivity.
E) type III hypersensitivity.

Question

Quizplus · Accepted Answer

This delayed reaction is characteristic of type IV hypersensitivity, also known as delayed-type hypersensitivity, which involves T-cell mediated immune responses and typically manifests 24-48 hours after exposure to the antigen.

A Small Amount of Antigen Is Injected Under the Skin