LJI scientists get first glimpse of how mysterious particles break off of immune cells

Jan. 5, 2021

Researchers at La Jolla Institute for Immunology (LJI) have found that people with sepsis have never-before-seen particles in their blood. The scientists said these particles, called elongated neutrophil-derived structures (ENDS), break off of immune cells and change their shape as they course through the body, according to a press release from LJI.

The research, published in the Journal of Experimental Medicine, shows the importance of understanding how immune cells change over the course of a disease.

“ENDS are not normal – they are not detectable in healthy people or mice,” said LJI Professor Klaus Ley, MD, who served as senior author of the study. “But ENDS are very high in sepsis, and I would not be surprised if they were high in other inflammatory diseases.”

The LJI team developed a series of new techniques to study how ENDS form and degrade – and to detect them in human and mouse blood plasma.

The researchers showed that these ENDS curl against the vessel wall until they get a rounded shape. It’s likely that the ENDS stay intact for a while, but not for long. Without any life-sustaining organelles inside, the ENDS begin to die. In fact, the researchers found that the ENDS secrete tell-tale signaling molecules that promote inflammation.

Sepsis can occur when the immune system overreacts to an infection by flooding the body with dangerous chemicals. Instead of just fighting the infection, these chemicals trigger organ damage as they course through the bloodstream. The mortality rate for septic “shock” is 30 percent.

Ley said it is theoretically possible that ENDS could one day serve as a biomarker for early sepsis detection, but it is currently impossible to detect them in a clinical setting. “Right now, the assay is not practical because it takes specialized instrumentation,” Ley said.

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