The normally harmonious balance of the immune system can be disturbed by cancer. A new report in the July issue of Nature Immunology shows how late-stage tumors can promote the development of 'suppressor' cells that prevent other immune cells from effectively fighting against the tumor.
Tumors can produce many types of abnormal proteins, some of which enable them to grow rapidly, whereas others may affect immune cells that are supposed to attack the tumor. In some cases, tumor products can serve as 'tumor beacons', alerting the immune system that danger is present and stimulating effective tumor immunity.
Spies and colleagues demonstrate a potentially harmful effect of one particular protein when overproduced by the tumor: it can spur otherwise helpful immune cells, called T helper cells, to divide and become suppressor cells that inhibit the activity of other immune cells. Exactly how the T helper cells become suppressor cells is not yet known. But the requirement for the tumor-derived protein in their production is clear and emphasizes the many ways that cancer cells can be detrimental to immune cells.
Thomas Spies (Fred Hutchinson Cancer Research Center, Seattle, WA USA)
Abstract available online.
(C) Nature Immunology press release.
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