The immune system is the defense of our body, and the immune cells in it are the core force to resist the tumor cells of the mutineers. So, how do immune cells attack and destroy cancer cells?

The internationally renowned journal "Nature" has produced an exquisite video, taking melanoma as an example, and telling everyone how immune cells in the human body eliminate tumor cells step by step from the perspective of tumor immunity.

01
The main force of the immune system to kill the enemy: immune cells

Many genes and environmental factors can cause tumors. For example, ultraviolet rays from the sun can damage DNA and other structures in melanocytes. Melanocytes are the cells that produce pigments in the skin.

Chronic damage to melanocytes from ultraviolet rays is actually the main cause of a skin cancer called melanoma. When melanomas begin to grow, they can eventually migrate to other locations in the body, such as the liver and lungs. .

The cells in the immune system are actually monitoring the tissues in our body. Natural killer cells (NK cells) release molecules related to stress response to these damaged cancer cells.

Dendritic cells, or DC cells for short, can activate cytotoxic T cells. These cytotoxic T cells can use their T cell receptors and other accessory receptors to present tumor-related antigens.
 
Once activated, NK cells and cytotoxic T cells will release perforin and granzyme, these molecules can perforate the surface of tumor cells, thereby causing them to undergo apoptosis.
 
Helper T cells also play a role in these reactions. They help DCs (dendritic cells) activate cytotoxic T cells, while also releasing cytokines such as gamma interferon to recruit more natural killer cells.

02
Why is the tumor so difficult to be strangled?

If the genes of tumor cells are changed, it is possible to make them survive, which also means that tumor cells are often heterogeneous.

For example, through genetic changes, tumor cells may no longer express those molecules recognized by NK cells. When the immune system continues to encounter these variant tumor cells, it can find that the cells it cannot perceive become more and more. Many, this is the concept of immune editing.

At the same time, this also leads to the appearance of tumors that cannot be recognized by the immune system.
 
Some tumor cells will highly express some molecules that inhibit the activity of T cells, and these molecules will bind to some receptors on T cells and inhibit their activity.

In addition, tumor cells can also attract immune cells that have the function of suppressing other immune cells to promote tumor growth. These immunosuppressive cells include regulatory T cells and other specific types of bone marrow cells.

Therefore, the tumor microenvironment is like a battle from the corresponding immune response. The immune system actually attacks tumor cells on the one hand, and helps it grow on the other hand.

03
To eliminate tumors, immunotherapy has a trick

Scientists are studying immunotherapy to strengthen the attacking effect of the immune system.

Since one cell is not strong enough, then find a way to "cultivate" more immune cells.

This method is ACTL immune cell therapy. Those cytotoxic T cells that can effectively attack tumor cells are selected from the patient's body. The strongest cytotoxic T cells (after cultured and proliferated) will be reinjected back into the patient.

Treatment with cytokines such as interleukin II and interferon alpha can also enhance the activity of anti-tumor immune cells in patients.

Of course, not all patients will respond to immunotherapy, and these treatment responses will also be delayed.

Combining immunotherapy with chemotherapy and radiation therapy can often achieve better therapeutic effects in some patients. Immunotherapy itself can also be used in combination. For example, if combined with blockers, it can be used together. Promote the occurrence of treatment response.

This therapy based on the principle of strengthening immune function may also be harmful. For some patients, the strengthened immune system will also attack their normal cells. Nevertheless, the results of many current clinical trials are very exciting. Yes, although this animation has been introduced around melanoma, immunotherapy is slowly being proven to be used to treat a variety of cancers.