Ins and outs of anti-Aspergillus serology in chronic pulmonary aspergillosis: a narrative review.

BACKGROUND: Chronic pulmonary aspergillosis (CPA) encompasses a spectrum of progressive lung diseases occurring in patients with prior structural lung damage. Despite prolonged antifungal therapy, CPA carries a 5-year mortality of one-third to one-half. Clinical symptoms are nonspecific, and radiological signs often overlap with those of the underlying disease. Direct microscopy and conventional culture are important but insensitive. Consequently, anti-Aspergillus IgG serology is the cornerstone of CPA diagnosis. OBJECTIVES: To review available anti-Aspergillus antibody assays for CPA diagnosis, the factors affecting their performance and interpretation, and their potential role in patient follow-up. SOURCES: PubMed was searched through July 2026 using combinations of "Aspergillus", "IgG", "antibody", "serology", and "chronic pulmonary aspergillosis". Manufacturer documentation was also reviewed for assay characteristics. CONTENT: Multiple enzyme immunoassay platforms exist, alongside manual methods, such as immunoprecipitation, immunoblot, and immunochromatographic tests. Although anti-Aspergillus IgG is central to CPA diagnosis, assay performance and interchangeability remain incompletely characterized. The lack of standardization in antigen sources (crude extracts versus recombinant proteins; A. fumigatus versus Aspergillus spp.), reported units (Arbitrary Units/mL, IU/mL, mgA/L, mg/L), and manufacturer cut-offs, together with the absence of an international reference standard, prevents cross-assay comparisons. In addition, interpretation is difficult because airway colonization, particularly in cystic fibrosis, bronchiectasis, chronic obstructive pulmonary disease, and asthma, may yield positive IgG results outside CPA. Moreover, radiological phenotypes, underlying conditions, notably corticosteroid exposure, and causative Aspergillus species contribute to variable sensitivities. IMPLICATIONS: Further work should prioritize assay standardization, locally validated cut-offs, and evaluation of serial serology alongside imaging, microbiology, and therapeutic drug monitoring.