In Uncontrolled Asthma, Blood Eosinophils May Hint at Lung Function

Higher blood eosinophil levels are associated with lower forced expiratory volume in one second (FEV1) reversibility among individuals with inadequately controlled eosinophilic asthma, according to a new study. Moreover, improvements in lung function for these patients may be possible with reslizumab treatment.


The study, which was authored by Dr J. Christian Virchow and colleagues, was presented at the American Academy of Allergy, Asthma & Immunology Annual Meeting on Saturday, February 23.


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To analyze eosinophil levels and lung function among individuals with low FEV1 reversibility to short-acting beta agonists (SABAs), the researchers gathered data from 2 year-long trials of intravenous reslizumab, 3 mg/kg once every 4 weeks, in patients with screening eosinophils of 400 μL or higher and reversibility to SABA of 12% or higher. Reversibility by baseline eosinophil category and lung function treatment effect were analyzed in both the lowest reversibility and highest eosinophil groups.


The 953 participants were categorized by baseline eosinophil level:

  • Less than 150 μL (n = 65),
  • 150-400 μL (n = 179),
  • 400-700 μL (n = 365), and
  • 700 μL or more (n = 344)


Participants were also categorized by baseline reversibility:

  • Less than 14% (n = 149),
  • 14%-20% (n = 276), and
  • 20% or higher (n = 528).

After analyzing the data, the researchers determined that participants with higher eosinophil levels had lower mean reversibility and a higher proportion with reversibility of lower than 14% compared with participants with lower eosinophil levels.


By comparing the treatment effects of reslizumab with placebo at week 52, the researchers were also able to determine that reslizumab treatment made clinically significant improvements in lung function outcomes.


“Reslizumab may reverse relatively ‘fixed’ airway obstruction in these patients,” the researchers concluded.


—Colleen Murphy



Virchow JC, Hickey L, Garin M. High peripheral blood eosinophil (EOS) levels are associated with low FEV1 reversibility (REV) in patients with severe eosinophilic asthma. Paper presented at: American Academy of Allergy, Asthma & Immunology Annual Meeting; February 22-25, 2019; San Francisco, CA. Accessed February 25, 2019.