The relationship between airway immunoglobulin activity and eosinophils in COPD

Thomas Southworth, Andrew Higham, Umme Kolsum, Jian Li, Thomas Scott, Josiah Dungwa, Sriram Sridhar, Tuyet‐Hang Pham, Paul Newbold, Dave Singh

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In chronic obstructive pulmonary disease (COPD), the effects of inhaled corticosteroids are predicted by blood eosinophil counts. We previously briefly reported increased immunoglobulin (Ig)A and IgM levels in bronchoalveolar lavage (BAL) of COPD patients with higher (eosinophil high) compared to lower (eosinophil low) blood eosinophils (>250/μL versus < 150/μL), suggesting differences in adaptive immune function. An inverse relationship exists between eosinophil counts and airway pathogenic bacteria levels. The mechanistic reasons for these associations between eosinophils, corticosteroids and pathogenic bacteria are unclear. IgA, IgM and IgG levels were assessed in BAL, bronchial biopsies and epithelium collected from eosinophil high (n = 20) and eosinophil low (n = 21) patients. Bronchial B-cell numbers were measured by immunohistochemistry. B-cell activity was assessed in bronchial samples and following exposure to BAL from eosinophil high and eosinophil low patients. BAL levels of non-typeable Haemophilus influenza (NTHi)-specific immunoglobulins were quantified. Results showed airway expression of IgA, IgG1 and IgM were lower in eosinophil low compared to eosinophil high patients, with lower levels of NTHi-specific IgA and IgM. Bronchial B-cell numbers were similar in both groups, but B-cell activity was lower in eosinophil low patients. In conclusion, COPD eosinophil low patients show differences in adaptive immune function compared to COPD eosinophil high patients. These differences may cause different microbiomes in these COPD phenotypes.

Original languageEnglish
Pages (from-to)2203-2212
Number of pages10
JournalJournal of cellular and molecular medicine
Issue number4
Early online date14 Feb 2021
Publication statusPublished - 27 Feb 2021


  • B-lymphocytes
  • haemophilus influenza
  • immunoglobulin A
  • immunoglobulin G
  • immunoglobulin M


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