Question

There are two ways to induce a process of self-destruction in a cell, which is called _________________:

• Cytotoxic T cells look for the presence of MHCs with foreign antigens and release ____________ and
_______________ or they bind to an __________ _____________ receptor (Fas receptor) on the surface
of the cell.
• Natural killer cells look for the absence of _____________ and are thus able to eliminate abnormal cells
that cytotoxic T cells cannot detect.

Answer 1

In the process of self-destruction known as apoptosis, cytotoxic T cells use perforin and granzymes or Fas receptors to destroy abnormal cells, while NK cells target cells lacking MHC I molecules.

Step-by-step explanation:

There are two ways to induce a process of self-destruction in a cell, which is called apoptosis: Cytotoxic T cells look for the presence of MHCs with foreign antigens and release perforin and granzymes or they bind to an apoptotic surface receptor (Fas receptor) on the surface of the cell. Natural killer cells look for the absence of MHC I molecules and are thus able to eliminate abnormal cells that cytotoxic T cells cannot detect.

Cytotoxic T cells and Natural Killer (NK) cells are crucial components of the immune system. Cytotoxic T cells search for cells with specific pathogen epitopes presented by MHC I molecules and kill them using perforin and granzymes, inducing apoptosis. Alternatively, they can bind to Fas receptors triggering a different apoptosis pathway. Meanwhile, NK cells detect cells that have downregulated MHC I molecules—a sign that could indicate infection or transformation to cancer cells—and destroy those cells. Together, these cell types work to maintain the health of the organism by eliminating potentially harmful cells.

Learn more about Apoptosis