A new study by researchers at the Karolinska Institute and Lund University indicates that the cytokine interleukin 26 (IL-26) could be used as a biomarker for uncontrolled asthma in both adults and children.1 Cytokines are proteins that are important to intracellular signaling among cells in the body’s immune system.

Several hundred million people around the world have asthma, and the disease is a leading cause of death in many countries. An estimated 10% of Swedes suffer from asthma at a cost of around $3 billion annually. Drugs for treating asthma don’t help a certain number of sufferers who have uncontrolled asthma, and researchers around the world continue to study the disease’s underlying causes.


Anders Lindén, MD, PhD, Karolinska Institute.

In their study, Anders Lindén, MD, PhD, professor of environmental medicine at the Karolinska Institute, and Leif Bjermer, MD, PhD, professor of respiratory medicine and allergology at Lund University, examined the presence of the cytokine IL-26 in adult patients with asthma. The work is a continuation of previous studies of IL-26, in which Lindén’s research team detected higher levels of local IL-26 in the airways of certain children with uncontrolled asthma.

The study results showed similarities between adults and children. On average, there were substantially higher levels of local IL-26 in the airways of subjects with uncontrolled asthma, when compared with subjects with controlled asthma. This finding is clear, even though both patient groups were being treated with antiinflammatory drugs and bronchodilators that conform to the most recent international guidelines.

“At the same time, we are showing that all patients with asthma, regardless of the severity of the disease, have an on average lower local level of IL-26 than healthy subjects do,” says Lindén. “We think that this latter finding is very interesting since we have found in a previous study that IL-26 contributes to the mobilization of important antibacterial cells, or neutrophils, during an infection. It is a long-known fact that all patients with asthma have an increased vulnerability to bacterial infections.”

In the patient group with uncontrolled asthma, the researchers noted that the patients with the poorest disease control were characterized by a low local level of IL-26—a finding that the researchers believe might indicate that IL-26 has a protective effect, and that these patients lack the ability to react with adequate production of IL-26. In the group of patients with asthma as a whole, the researchers found a negative correlation between a local level of IL-26 and lung function and the presence of inflammatory cells other than neutrophils.

“In light of existing experimental literature, these findings could be interpreted as a general increase of local IL-26 as a consequence of severe asthma and that it in fact has a protective effect against inflammation,” Lindén says. “The generally lower level compared with healthy persons could then be due to the long-term cortisone treatment that the majority of patients with asthma receive. All in all, our new research results indicate that IL-26 might be a useful biomarker for uncontrolled asthma in adults as well as children, something that could benefit future medical care.”

For more information, visit Karolinska Institute.


  1. Tufvesson E, Jogdand P, Che KF, et al. Enhanced local production of IL-26 in uncontrolled compared with controlled adult asthma. J Allergy Clin Immunol. Epub ahead of print, July 6, 2019; doi: 10.1016/j.jaci.2019.06.035.

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Asthma medication. Set of inhalers and medication for the treatment of bronchial asthma. Photo © Barmalini courtesy Dreamstime (ID 69460928).