Activation status of airway immune cells is a defining feature of severe asthma, regardless of fungal sensitisation.

Airborne fungi are potent inducers of respiratory disease and cause the debilitating conditions severe asthma with fungal sensitisation (SAFS) and allergic bronchopulmonary aspergillosis (ABPA). However, the immune cell types and the inflammatory airway environment that defines SAFS and ABPA patients is not extensively characterised. To address this, we recruited SAFS and ABPA patients, asthmatics without evidence of fungal sensitisation and healthy controls (n = 20 individuals per group). Immune cells were isolated from collected sputum and peripheral blood samples and immunophenotyping was performed via flow cytometry. By applying a machine learning approach to our dataset, we identify a critical association between CD4+ T cells, type 2 conventional dendritic cells, eosinophils, proinflammatory factors and severe respiratory disease. These complex immune signatures should be investigated further to improve the diagnostics and treatment of SAFS and ABPA.