The second most common human autoimmune disease, systemic lupus erythematosus (SLE), is marked by overproduction of antibodies against the body's nucleic acids. Two studies show that white blood cells called neutrophils from patients with lupus release a network of DNA-rich fibres called neutrophil extracellular traps (NETs) that may sustain the disease.

Virginia Pascual at the Baylor Institute for Immunology Research in Dallas, Texas, and her colleagues found that neutrophils from children with SLE die in vivo at higher rates than those from healthy individuals. When exposed to antibodies found in the blood of patients with SLE, dying neutrophils produce NETs that activate cells called plasmacytoid dendritic cells. These produce high levels of interferon-α — which triggers immune responses, thus priming more neutrophils to release more NETs.

Michel Gilliet at the University of Texas, Houston, and his colleagues showed that people with lupus also generate antibodies against antimicrobial peptides carried by NETs, suggesting that the NETs trigger additional autoantibody production.

Sci. Trans. Med. 3, 73ra19 (2011) ; Sci. Trans. Med. 3, 73ra20; (2011)