Increased total, secretory and NTHi-specific IgA in the COPD airway

Abstract

Non-typeable Haemophilus influenzae (NTHi) can colonise the COPD airway. Previous work has suggested that the ability of NTHi to survive is due to deficient release of secretory (s)IgA into the airway lumen1. The aim of our study (NCT01701869) was to quantify the amount and functionality of IgA in bronchoalveolar lavage (BAL). Bronchoscopy was performed on 24 mild-to-moderate COPD patients and 8 age-matched healthy controls (HC) and BAL and protected specimen brushes were collected. NTHi was cultured from protected specimen brushes from 5 of the COPD patients (21%). Total BAL IgA was assessed by MSD with median values in HC of 2.4 µg/ml. IgA was significantly increased in NTHi- COPD patients (17 µg/ml, p These data indicate that NTHi colonisation can occur in COPD patients despite higher levels of total, secretory and NTHi-specific IgA. These observations suggest that the true correlate of protection in the COPD airway remains to be characterised and that colonising NTHi may escape humoral immunity. 1. Polosukhin et al (2011) AJRCCM.