Final answer:
The Single Intradermal Comparative Cervical Tuberculin test (SICCT) is an example of a Type IV hypersensitivity reaction, also known as delayed-type hypersensitivity, and it is used to detect exposure to Mycobacterium tuberculosis.
Step-by-step explanation:
The Single Intradermal Comparative Cervical Tuberculin test (SICCT) is an example of a Type IV hypersensitivity reaction, specifically a delayed-type hypersensitivity (DTH). This test is commonly used to detect exposure to Mycobacterium tuberculosis. The SICCT involves the injection of bacterial proteins from M. tuberculosis into the skin, and a positive reaction is characterized by a raised, hard red area, called an induration, which occurs a couple of days later due to an accumulation of activated macrophages and T cells. This immune response is a result of the reactivation of memory T cells indicating past or present exposure to the bacteria.