• Stephanie T Yerkovich, Belinda J Hales, Melanie L Carroll, Julie G Burel, Michelle A Towers, Daniel J Smith, Wayne R Thomas, and John W Upham.
• School of Medicine, The University of Queensland, Brisbane, Australia.
• BMC Pulm Med. 2012 Jan 1;12:37.

BackgroundAcute exacerbations of chronic obstructive pulmonary disease (AECOPD) are often linked to respiratory infections. However, it is unknown if COPD patients who experience frequent exacerbations have impaired humoral immunity. The aim of this study was to determine if antibodies specific for common respiratory pathogens are associated with AECOPD.MethodsPlasma was obtained from COPD patients when clinically stable. AECOPD requiring hospitalisation were recorded. IgG1 antibodies to H. Influenzae outer membrane protein 6 (P6), pneumococcal surface protein C (PspC) and the VP1 viral capsid protein of rhinovirus were measured.ResultsCOPD patients who had an AECOPD (n = 32) had significantly lower anti-VP1 IgG1 antibody levels when stable compared to COPD patients who did not have an AECOPD (n = 28, p = 0.024). Furthermore, the number of hospitalisations was inversely proportional to anti-VP1 antibody levels (r = -0.331, p = 0.011). In contrast, antibodies specific for P6 and PspC were present at similar concentrations between groups. Plasma IL-21, a cytokine important for B-cell development and antibody synthesis, was also lower in COPD patients who had an AECOPD, than in stable COPD patients (p = 0.046).ConclusionDeficient humoral immunity specific for rhinoviruses is associated with AECOPD requiring hospitalisation, and may partly explain why some COPD patients have an increased exacerbation risk following respiratory viral infections.

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