The following features is common to both cytotoxic T cell and NK cell
**Core Concept**
Cytotoxic T cells and Natural Killer (NK) cells are both types of lymphocytes that play a crucial role in the immune system's ability to recognize and eliminate infected cells or tumor cells. They share a common mechanism of action, which involves the recognition of target cells and the subsequent release of cytotoxic granules.
**Why the Correct Answer is Right**
Both cytotoxic T cells and NK cells recognize target cells through the interaction of specific cell surface receptors with ligands on the target cell. This recognition process triggers a signaling cascade that leads to the activation of cytotoxic granules, which contain proteins such as perforin and granzymes. Perforin forms pores in the target cell membrane, allowing granzymes to enter and induce apoptosis (programmed cell death). This mechanism is essential for eliminating infected cells or tumor cells from the body.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because cytotoxic T cells require antigen presentation via MHC class I molecules to recognize target cells, whereas NK cells do not require antigen presentation.
* **Option B:** This option is incorrect because while both cytotoxic T cells and NK cells can induce apoptosis, they use different mechanisms to do so. Cytotoxic T cells use the perforin/granzyme pathway, whereas NK cells use the Fas/FasL pathway.
* **Option C:** This option is incorrect because while both cytotoxic T cells and NK cells can recognize target cells through cell surface receptors, they recognize different types of receptors. Cytotoxic T cells recognize MHC class I molecules, whereas NK cells recognize MHC class I molecules in a non-self context.
**Clinical Pearl / High-Yield Fact**
Cytotoxic T cells and NK cells play a crucial role in eliminating infected cells or tumor cells from the body, and their dysfunction can lead to immunosuppression and an increased risk of infections or cancer. Understanding the mechanisms of action of these cells is essential for developing effective immunotherapies for various diseases.
**Correct Answer:** None of the above options are correct. The correct features common to both cytotoxic T cells and NK cells include the recognition of target cells through cell surface receptors and the subsequent release of cytotoxic granules, but these options are not listed.