A chemical "danger receptor" on certain specialized cells senses the cell death characteristic of bodily injury or malignant tissue and then mobilizes the body's immune system to repair the flaw, a recent study has revealed.
The results, which were reported in the journal Nature, may explain the mechanism behind some cancer-fighting drugs that partly work by stimulating an immune response. The scientists, based at Cancer Research UK's London Research Institute, in Britain, speculated that knowledge of the receptor could assist in developing strategies to use the immune system to shrink tumors.
Cell death is a normal bodily process in which simply the old cells make way for the new, rejuvenating tissues. But abnormal cell death occurs when a body part is injured or when cells die in the interior portions of a tumor where blood flow is cut off. Scientists have theorized that the body somehow senses this form of cell death (necrosis) and stimulates an immune response.
In the recent study, the research team found a chemical receptor, called DNGR-1, on dendritic cells. These are cellular components of the immune system. They sense antigens, or abnormal chemicals, and then signal the immune system's actual "killer" cells as to what to go out and destroy, whether viruses, bacteria, etc.
"After a 15-year hunt, we've identified the first 'danger receptor' - one which senses abnormal cell death and then triggers an immune response," said Caetano Reis e Sousa, the paper's chief author. "The detection of 'danger' could explain some situations when a tumor triggers an immune reaction against itself."
Manipulating this system, he said, could help not only in treating cancer but also in areas such as the prevention of rejection in organ transplantation.
"There is a theory that some cancer-killing drugs kill tumor cells in such a way that triggers the immune system against them so they have a double whammy."
Lesley Walker, director of information at Cancer Research UK, said, "The concept of using the body's immune system to fight cancer has been around for decades, but advances in recent years have made this field of research a very exciting one. The results of this study are really important scientifically and a step towards understanding how to manipulate the immune system to treat cancer in the future."
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