The existence of resident fungal communities (‘mycobiome’) within the lungs has only recently been discovered. These commensals are disrupted in the context of chronic lung conditions such as COPD (chronic obstructive pulmonary disease) but virtually nothing is known about their role in shaping airway immunity. We are combining fungal and immune profiling within unique human airway samples with experiments in mouse models to identify roles played by fungal commensals in health and disease.