Dendritic cell dysfunction, including impaired IL-12 production, is associated with chronic pulmonary aspergillosis.

Background: Growing evidence links immune dysfunction, notably impaired IFNγ production, to chronic pulmonary aspergillosis (CPA), but understanding of the immune phenotype in CPA patients remains limited.

Methods: To investigate this, we recruited 25 CPA patients and 25 controls with bronchiectasis, isolating immune cells from peripheral blood for detailed flow cytometric phenotyping at resting state and after ex vivo stimulation with the TLR2/Dectin-1 agonist Zymosan.

Results: CPA patients exhibited pronounced neutrophilia and a reduced frequency of conventional dendritic cell (DC) subsets at baseline compared to bronchiectasis controls. Post-stimulation, DC and monocyte subsets in CPA patients showed significantly lower expression of activation markers. Notably, cDC1s displayed reduced IL-12p40, TNFα, and CD86 expression. CPA patients with a history of tuberculosis (TB) had significantly higher frequencies of activated cDC1s. Machine learning analysis validated these immunological parameters as predictive of CPA status.

Conclusion: Our findings suggest that immune dysfunction in CPA involves DC and monocyte impairments, potentially contributing to IFNγ deficiency through reduced IL-12 production and co-stimulatory capacity in cDC1s. These results also hint at the presence of innate immune memory in CPA patients with prior TB. Our study advances understanding of the immune dysfunction underlying CPA.