How are natural killer (NK) cells different from cytotoxic T (TC) cells?
A) NK cells induce apoptosis in their target cells, whereas TC cells are professional phagocytes.
B) NK cells kill virus-infected cells, whereas TC cells kill cancerous cells.
C) NK cells kill cells with a high level of class I MHC protein expression, whereas killing by TC cells requires low expression levels.
D) NK cells respond quickly to a virus infection, whereas the activation of TC cells to become cytotoxic is a slow process.
E) NK cells are normally abundant in the tissue even before infection, whereas TC cells are mostly in the bloodstream.

Question

Quizplus · Accepted Answer

NK cells are components of the innate immune system, which responds quickly to infection; NK cells circulate in a partially active state and therefore can kill virally infected cells when they first encounter them. TC cells need to be activated in a slow process in a lymphoid organ before they can kill virus-infected cells.

How Are Natural Killer (NK) Cells Different from Cytotoxic T