Tuesday, April 9, 2013

Artificial immune cells used to destroy tumours

Our immune system is tasked with guarding our body against foreign invaders such as bacteria or viruses. Less commonly known is that immune cells also keep a close eye on the way our body functions. Cells that go haywire are swiftly removed from the tissues and are consequently replaced by healthy cells. However, the immune system does not always recognize those cells that need to be cleared, and in such cases a tumour may arise: cancer cells have found a way to escape detection and can therefore proliferate and endanger our health. Scientists from the University of Pennsylvania have found a way to modify immune cells in such a way that they recognize and destroy tumours.

In their studies, the scientists made use of T cells, which are responsible, among other things, for killing malicious cells. They were modified to express a receptor on the cellular surface called CAR. This allowed them to build in another component that specifically recognizes cells that belong to a tumour. By doing that, the scientists showed capable of engineering immune cells that specifically recognize malicious cells, but leave healthy tissues alone.

A special class of molecules is involved with the recognition of malicious cell types, and are called antibodies. Normally, they are produced by so-called B cells, family of the T cells, and bind to whatever it is they are made to recognize. At the University of Pennsylvania, they generated tumour-specific antibodies and grafted those on the CAR domain of the T cells. By doing that, they made a vicious killer cell that only targets the tumour it is made to recognize. A wide range of different artificial T cells can be constructed by using different antibodies, so that the cells can be used for a wide range of cancers.

No clinical tests have been performed yet, which means it is currently unclear whether the artificial T cells will ever find their way into the clinic. Animal experiments have already been attempted however, and the scientists showed that their engineered cells persist in the blood and are capable of killing human cancer cells. Such conclusions can be made because it is possible to graft animals with human tumours, in order to create experimental models that more closely resemble the situation in the clinic. All in all, the attempt is promising, and it might  be a way to upgrade our immune system to prevent cancer.
This is what happens when a T cell (killer cell) recognizes its target. It binds to its victim to release deadly compounds that destroy the target cell.

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