Wednesday, May 28, 2008

Cancer Vaccine Target Pinpointed

Scientists may be one step closer to producing a specific targeted vaccine for killing cancer cells.

UK researchers have identified a unique protein, known as DNGR-1, on immune cells which they hope will help them harness the body's defences to attack a tumour. A vaccine designed to "home in" on the protein would then deliver a message to the immune system to attack the invading cancer. The research is published in the Journal of Clinical Investigation.

The protein is unique to a type of immune cell called a dendritic cell, which is responsible for triggering the body's defence system. Its job is to present pathogens or foreign molecules to other cells of the immune system, which in turn eliminate them.

The results of this research are an important step towards understanding how to create targeted cancer vaccines in the future. The team at Cancer Research UK's London Research Institute said scientists have been searching for proteins or "tags" on dendritic cells for over 30 years.

Dendritic cells are now recognized as the gatekeepers of the immune response, possessing a unique potential for acquisition of antigens at extremely low exposure levels and for efficient presentation of these in an immunogenic form to the naive T-cell system.

In theory a vaccine carrying a foreign molecule from a cancer cell could be targeted to the dendritic cells, which would then prompt the immune system to attack the "invading" cancer. The same approach could potentially be used for treating other diseases such as HIV or malaria.

Vaccines work by triggering an army of immune cells, called T cells, to attack potentially dangerous foreign molecules, like those found on pathogens. Dendritic cells are the messengers, telling the T cells who to attack. The vaccine will carry a sample of the offending molecule and deliver it to DNGR-1 on the dendritic cells, which in turn will present the molecule to the armies of T cells and instruct them to attack.

Although many vaccines have been tested in the clinical, few have proven successful so far. Part of the problem is locating the right target to effectively start the attack reaction over prolonged periods of time. The results based on a more targeted approach will be interesting.

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