Regulatory T Cells Hamper Fight Against Cancer

Researchers have found that while some cancer patients develop specific cytolytic lymphocytes that should destroy their tumors, these cells are prevented from acting due to a chemical signal transmitted by another set of immune cells called regulatory T cells. The finding was published in the September 15, 2002, issue of Cancer Research.

Studies of the interaction between human colorectal cancer cells and immune cells revealed that transforming growth factor (TGF-beta) was the chemical messenger that prevented cytolytic T cells from acting. The researchers say a drug that inactivates the regulatory T cells or that blocks the TGF-beta chemical message they send might free the cytolytic T cells to attack a patient's tumor.

"We have known for some time that cancer patients can generate T cells able to attack their tumors,” explained senior author Dr. Dorothee Herlyn, a professor at The Wistar Institute (Philadelphia, PA, USA; www.wistar.edu). "What we discovered in this study is that those patients also produce negatively regulating cells at the same time that keep the attacking T cells in check. The existence of these regulatory cells may help explain how tumors are able to evade the immune system. They also represent a new starting point for thinking about novel anticancer treatments.”




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