Which CD8+ T-cells in asthma? Attacking or defending?

Even though there have been multiple studies with longitudinal assessment of lung function in asthma [1, 2], to date, the relationship between the underlying airway pathology and the rate of functional decline has been poorly addressed in prospective studies. DEN OTTER et al. [3], in the present issue of the European Respiratory Journal, have addressed this topic in a cohort of patients with mild-to-moderate asthma who were followed for 14 years, and underwent bronchoscopy at the beginning of the study and at the end of follow-up. The numbers of CD8 and CD4 cells in bronchial biopsies at baseline correlated with the subsequent decline in lung function. The subjects with the highest function decline had higher counts of CD3 and CD8 T-cells and presence of granzyme B in biopsies taken at follow-up. Let’s consider two aspects of this study.