New research from Brigham and Women’s University Hospital offers an explanation as to why patients with severe asthma may not find relief from corticosteroids.

Duvall, Levy and colleagues examined immune cells in samples from patients with severe asthma, patients with non-severe asthma and healthy control subjects. They focused on a prominent type of white blood cells: lymphocytes. One important family of innate lymphocytes in the lung are known as natural killer (NK) cells, which are pivotal for both mounting an immune response and helping to resolve inflammation.

In patients with severe asthma, however, NK cells are disabled from resolving inflammation, and become outnumbered by other types of immune cells that provoke inflammation. Treatment with corticosteroids appeared to further suppress the ability of severe asthma NK cells to help clear inflammation.

“By the actions of corticosteroids on NK cells, patients with severe asthma who are on corticosteroids may be experiencing the side effects of the drug without receiving significant benefit,” said Levy.

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