Circulating Mitochondrial DNA Alerts Immune System to Danger

In response to short DNA fragments, lymphocytes release mitochondrial DNA that helps trigger an immune response.

katya katarina zimmer
Katarina Zimmer

After a year teaching an algorithm to differentiate between the echolocation calls of different bat species, Katarina decided she was simply too greedy to focus on one field. Following an internship with The Scientist in 2017, she has been happily freelancing for a number of publications, covering everything from climate change to oncology.

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SPIDEY SENSE: Lymphocytes ejected weblike, fluorescing strands of mitochondrial DNA (green) when exposed to certain oligonucleotides. PNAS


B. Ingelsson et al., “Lymphocytes eject interferogenic mitochondrial DNA webs in response to CpG and non-CpG oligodeoxynucleotides of class C,” PNAS, 115:E478-87, 2018.

Beyond acting as a genetic blueprint, DNA can play a direct role in the immune system. For instance, neutrophils cast webs of DNA and antibacterial proteins into the bloodstream to trap pathogens. When a team of Swedish researchers observed that B lymphocytes also appear to eject DNA, they decided to investigate further.

The researchers isolated several types of lymphocytes—B cells, T cells, and natural killer cells—from healthy blood donors and leukemia patients. They exposed them to a variety of triggering molecules, such as ionomycin from Streptomyces conglobatus, together with a fluorescent DNA-binding substance in vitro. Only when exposed...

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