The immune system is a complex defense system whose main function is to protect the body against external agents. It is important to be able to differentiate the own components, from the organism of the same person, from the others.
In the same way, the immune system is also capable of identifying and combating cellular components of its own. This happens when these components turn out to be abnormal. This is the case of cancer cells, which differ from the normal cell.
It is important to understand that in all types of cancer, the process of the disease is that some cells of the body begin to divide without stopping and spread to nearby tissues. Cancer is a dangerous disease and it is very important to have professional help to fight it properly.
Immune system functions
In addition to recognizing and fighting tumor cells, the immune system also has other ways of preventing its appearance.
- It protects against viral infections that can lead to the appearance of tumors. This is the case, for example, of the human papillomavirus. Among others, with great mutagenic potential, so that their infection can alter the genetic material of the cells.
- It fights by eliminating external pathogens. When there is an infection, the body responds by developing an inflammation around it. However, this inflammation must be resolved effectively because this environment can sometimes lead to the appearance of tumors.
- Identify and eliminate cancer cells. This is through specific markers.
But how does the immune system recognize cancer cells? The answer lies in some surface proteins, present in all cells, called surface antigens.
The surface antigens of tumor cells are different from those of healthy cells. Thus, the cells of the immune system can recognize these antigens and detect when they correspond to a mutated cell.
The immune cells capable of carrying out such recognition task are the T lymphocytes. These T lymphocytes possess a series of receptors that detect the surface antigens.
Immune cycle against cancer
The response of the immune system to cancer begins with the recognition of mutated cells, thanks to the aforementioned surface antigens. These antigens are examined by the T lymphocytes, present in the lymph nodes.
After this, the T lymphocytes undergo a series of changes and become active. This gives them the ability to mobilize and travel to the blood vessels. Through these, the T lymphocytes reach the tumor directed by gradients of concentration of certain signaling molecules.
Once they reach the tumor zone, the T lymphocytes infiltrate this region in order to attack it. Here they recognize the tumor cells that present certain proteins on their surface and proceed to their destruction.
This is achieved thanks to the stimulation of another series of cells of the immune system. For example, Natural Killler (NK) cells or macrophages.
Exhaust mechanisms of tumor cells
The reason that explains the development of cancer despite the performance of the immune system is that some cancer cells have accumulated so many mutations that have mechanisms to prevent the performance of the immune system.
These mechanisms allow tumor cells to hide from the immune system. For example, hiding surface antigens that could be recognized by it.
In these cases, the immune system can counterattack thanks to the Natural Killer cells. They are able to detect when a cell has lost its own surface antigens, recognize it as foreign and eliminate it.
Another mechanism that can be used by tumor cells to impede the action of the immune system is to produce chemical messengers with inhibitory action on immune cells. In this way, they create immunosuppression around the tumor area. This favors the survival of cancer cells.
For all this, the main objective of immunotherapy, is precisely to help the immune system to fight abnormal cells. This can be achieved with adjuvant therapy, which uses antibodies directed against the tumor cells, in order to favor their elimination.