How The Immune System Fights Cancer

The immune system is a complex defense system whose main function is to protect the body against external influences. It is therefore important that it can distinguish its own components from external components. This is how the immune system fights cancer.

Similarly, the immune system can also identify and fight its own cellular components. This happens when these components are abnormal. This is the case with cancer cells, which are different from normal cells.

It is important to understand that the disease process in all types of cancer consists of the uncontrollable division of a number of body cells and spreading to nearby tissues. Cancer is a dangerous disease, which is why it is very important to have professional help to fight it properly.

Functions of the immune system and how it fights cancer

The immune system is made up of a series of cells and mechanisms that prevent damage from outside influences. In addition to recognizing and fighting tumor cells , the immune system also has other ways to prevent them from appearing.

• It protects the body from viral infections that can lead to the appearance of tumors. This is the case, for example, with human papillomavirus (HPV). It also fights others with high mutagenic potential, meaning their infection can alter the genetic material of cells.

• It fights by eliminating external pathogens. If there is an infection, the body responds by developing inflammation around it. However, this swelling must be effectively remedied as this environment can occasionally lead to the appearance of tumors.
• Identifies and kills cancer cells. It does this through specific markings.

Surface antigens

How does the immune system recognize cancer cells? The answer lies in a number of surface proteins present in all cells, called surface antigens (Spanish link).

The surface antigens of tumor cells differ from those of normal cells. Thus, the cells of the immune system can recognize and detect these antigens when they correspond to a mutated cell.

The immune cells that are able to perform this recognition task are T lymphocytes (Spanish link). These cells have a number of receptors that detect surface antigens.

How the immune system fights cancer: the immune cycle

T cells can recognize the changes that mutated cells undergo. The immune system’s response to cancer begins with the recognition of mutated cells, thanks to the above-mentioned surface antigens. These antigens are examined by T lymphocytes present in the lymph nodes.

After this, the T lymphocytes undergo a series of changes and are then activated. This allows them to travel to the blood vessels. Through them, the T lymphocytes reach the tumor, which is controlled by concentration gradients of certain signaling molecules.

Once they reach the area of ​​the tumor, the T lymphocytes infiltrate that area to attack. Here they recognize the tumor cells that have certain proteins on their surface and proceed to destroy them.

They do this by stimulating a new set of cells of the immune system. For example, by stimulating Natural Killer (NK) cells or macrophages.

Escape mechanisms of tumor cells

Despite all efforts, malignant cells have mechanisms to avoid the immune system. The reason for the development of cancer, despite the functioning of the immune system, is that a number of cancer cells have undergone so many mutations that they have mechanisms to prevent the functioning of the immune system.

These mechanisms allow the tumor cells to hide from the immune system. For example, hiding the surface antigens that can be recognized by the immune system.

In these cases, Natural Killer cells allow the immune system to fight back. These cells can detect when a cell has lost its own surface antigen. So they recognize it as strange and eliminate it.

Another mechanism that tumor cells can use to prevent the functioning of the immune system is to produce chemical messengers that inhibit immune cells. In this way they create immunosuppression around the tumor. This promotes the survival of cancer cells.

For these reasons, the main goal of immunotherapy is precisely to help the immune system fight abnormal cells. This can be achieved with adjuvant therapy, which uses antibodies that target tumor cells to promote their elimination.