Why do many heavy smokers evade lung cancer while others who have never lit up die of the disease? The question has vexed scientists for decades. Now, new research at Washington University School of Medicine in St. Louis suggests a key immune cell may play a role in lung cancer susceptibility. Working in mice, they found evidence that the genetic diversity in natural killer cells, which typically seek out and destroy tumor cells, contributes to whether or not the animals develop lung cancer. The research was published in the September 1, 2012 issue of Cancer Research. “Overall, humans are genetically very similar, but their immune systems are incredibly diverse,” explains senior author Alexander Krupnick, M.D., a thoracic surgeon at the Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine. “Our findings add to the growing body of evidence suggesting that innate differences in immunity may determine not only a person’s susceptibility to colds but also to lung cancer.” Based on the findings in mice, Dr. Krupnick says he and his colleagues are now studying whether humans have a similar genetic diversity in their natural killer cells. As part of a new clinical study, they’re analyzing the blood of heavy smokers with and without lung cancer and never-smokers with and without lung cancer to look for differences. “We want to know whether heavy smokers who don’t get lung cancer have natural killer cells that are somehow better at destroying newly developing lung cancer cells,” says Dr. Krupnick, associate professor of surgery. “And, by comparison, do patients who have never smoked but develop lung cancer have weak natural killer cells?” For the mouse study, the scientists evaluated three groups of mice with varying susceptibilities to lung tumors.
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