What does your immune system do?
Your body's immune system keeps intruders at bay. If they do manage to enter the body, it's the job of white blood cells to clear them out. There are many different types of white blood cells. They all have a different task. For example, there are 'gatekeepers' that look at all kinds of cells and molecules in your body to determine whether they are dangerous. When they track down an intruder, the gatekeepers send a signal to the other white blood cells to attack.
Innate and acquired
Part of your immune system works straight away, from birth. This part reacts quickly, but does not work very specifically. It includes, for example, the mucous membrane in your nose where bacteria and viruses are trapped. When your finger starts throbbing after you've had a nasty cut, that's also the innate immune system at play.
The learned part of your immune system is smarter and more specific. Every time you come across a new invader, such as a virus or bacteria, your learned or acquired immune system remembers how to recognize that invader. Two important types of white blood cells in the learned defense system are T cells and B cells. These help with remembering and destroying intruders, among other jobs. If you encounter the same intruder another time, it can be cleared up quickly and effectively, and you won't become ill.
Sometimes the immune system doesn't work as it should. It might work against the wrong things, for example against your own cells. This is the case with diseases such as multiple sclerosis (MS) or arthritis. In the case of allergies, it reacts too strongly against intruders. The immune system is based on an important balance: it must recognize and clear invaders, but leave your body's own cells alone.
The immune system recognizes invaders with the help of a kind of 'flags' on the outside of all cells, called antigens. Every cell and every substance has a unique combination of flags on its surface: a skin cell, for example, has very different flags than a cell in the lungs. And all the cells of your own body have a 'this-is-me-flag'. These should be left alone.
Immune system and cancer
It may sound surprising, but cancer isn't actually an invader. A tumor starts when a normal cell in the body derails and continues to divide and grow unchecked. So when the immune system's gatekeepers come across a cancer cell, they often think they can let it through. Cancer cells also have all kinds of tricks to evade the immune system. That is why the immune system needs help in recognizing and destroying cancer cells: immunotherapy. This is a relatively new type of therapy that is used to treat some children and adults with cancer.
There are different types of immunotherapy. The most common forms are antibody therapy and cell therapy. In antibody therapy, the drug recognizes a flag that is unique to the cancer cells and sticks to it. This makes it much easier for the immune cells to recognize the tumor cells. Antibody therapy nudges the body's own defense mechanisms into action. The own immune cells arrive to the scene to attack and destroy the cancer cells. They also remember the flag on the cancer cells. This also makes them more alert if the cancer comes back. An example of antibody immunotherapy is anti-GD2 therapy. This drug is used in children with neuroblastoma.
In cell therapy, the own immune cells are trained against the cancer. T-cells, a type of white blood cell, are taken from the body and modified in the lab. The T-cells are programmed to specifically recognize and attack the cancer cells' code. They are put back into the body with an IV drip, where they start to attack the cancer cells. In cell therapy, too, the immune system remembers the cancer cells' signature code. This allows the immune system to attack again as soon as the cancer comes back. An example of cell therapy is CAR T-cell therapy. This is a form of immunotherapy given to some children with acute lymphoblastic leukemia (ALL).
Immunotherapy is the newest kind of treatment for cancer. Immunotherapy is now part of the standard treatment for some children with neuroblastoma or ALL. Some children are cured thanks to immunotherapy. Scientists are carrying out a lot of research into immunotherapy, in the Princess Máxima Center and in the rest of the world. They are trying to make these treatments work better for the children who are already eligible for them - because the treatment does not yet work for all children. And in some children, the immunotherapy stops working after a while, for example if the cancer cells change their code. Scientists are also doing a lot of research to see how we can make immunotherapy work for increasingly many different forms of cancer.
CAR T is a form of immunotherapy. This treatment is given to children with acute lymphoblastic leukemia (ALL) in which the B cells are affected and in whom chemotherapy does not work. CAR T-cells are best thought of as T cells with superpowers. Want to know exactly how this works? Researcher Stefan Nierkens explains it to you in this video.
With thanks to DREAM3DLAB/Princess Máxima Centre & Victor van Ineveld.