Macrophage Defector

Natural killer cells are a type of immune cell that protects the body against not only invading pathogens but also cancer, providing an innate defence against these rogue cells. Some tumours, however, keep natural kill cells at bay and thereby avoid destruction. And recent research in lung tumours reveals this natural killer cell exclusion is achieved with the help of another immune cell – the macrophage. The particular culprit is a type of macrophage covered in a protein called TREM2 – an anti-inflammatory factor. Shown above is a lung tumour (green) packed with TREM2-expressing macrophages (red) that are protecting the cancer from attack. Why these macrophages switch allegiance and side with enemy is unclear, but blocking TREM2 while boosting natural killer cell activity was shown to reduce lung tumour growth in mice suggesting a similar approach might be effective in promoting tumour regression in humans too.

Written by Ruth Williams

Ruth Williams

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Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

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• Image from work by Matthew D. Park and Ivan Reyes-Torres, and colleagues
• Marc and Jennifer Lipschultz Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
• Image copyright held by the original authors
• Research published in Nature Immunology, April 2023