New research explains why some tumors undetected

New research explains why some tumors undetected
LONDON (Reuters) - Researchers looking at immune systems inhealthy people have discovered an interaction between two typesof cells that may help explain why the body's natural defensesfail to detect and fight tumors.
The findings could lead to better cancer treatments and newtargets for drugs, said Leonie Taams, an immunologist at King'sCollege London, who led the study published on Tuesday.
The study looked at regulatory T-cells, which keep theimmune system stable and are key in controlling immune cellscalled macrophages that cause inflammation. Inflammation is oneof the body's first responses when fighting infection.
Taams said the study showed that just as regulatory "policeofficer" T-cells can stop killer T-cells from attacking atumor, they can also shut off macrophages, suppressinginflammation and keeping the body from detecting tumors.
"Before these police officers were never believed to speakto these macrophages. We have shown they can do it," Taams saidin a telephone interview.
"The regulatory T-cells trick the immune system intothinking there is no problem."
Scientists had known things like the presence of bacteriatypically activated macrophages but understood less about whatcaused the cells to switch off.
Taams said the study -- in which researchers tookmacrophages from healthy people and cultured them in disheseither on their own, with normal T-cells or with regulatoryT-cells -- answered that question for the first time.
Their findings, published in the Proceedings of theNational Academy of Sciences, could lead to better ways todetect whether someone's immune system is fighting a tumorafter treatment, she said.
It could also lead to more specific drugs aimed at removingor altering these non-inflammatory macrophages that suppressthe immune system's response, Taams added.
"The work was done in healthy people but we believe it hasimplications for cancer," she said. "We believe that theregulatory T-cells are doing the job they are supposed to dobut they are doing it at the wrong place and the wrong time."
"The findings provide more ammunition for the idea thatregulatory T-cells should be removed from tumors."
(Editing by Maggie Fox and Michael Winfrey)