Chlamydia pneumoniae immunoglobulin A reactivation and airway inflammation in acute asthma

Infection with Chlamydia pneumoniae can trigger acute asthma and is associated with severe chronic asthma. The aim of the present study was to examine the relationship between airway inflammation and serological response to C. pneumoniae in acute severe asthma. Subjects (n=54) were recruited within 4 h of presentation to the emergency department with an acute exacerbation of asthma. Clinical history taking, sputum induction (0.9% saline), spirometry and acute and convalescent serology for C. pneumoniae immunoglobulins A and G were performed. At presentation, 47% of subjects had antibodies directed against C. pneumoniae, and 38% (20) demonstrated an increase in C. pneumoniae antibody levels, with 15 demonstrating a rise in immunoglobulin A concentration. C. pneumoniae responders exhibited significantly higher sputum neutrophil levels (4.6 x 10(6) cells x mL(-1)) compared to nonresponders (1.2 x 10(6) cells x mL(-1), p=0.02) and elevated sputum eosinophil cationic protein concentration (3,981 versus 1,122 ng x mL(-1), p=0.02). An acute antibody response to Chlamydia pneumoniae is common in exacerbations of asthma. The serological features suggest that Chlamydia pneumoniae reactivation may trigger neutrophilic airway inflammation in acute asthma.