Role of Aspergillus IgG in Diagnosis and Management of ABPA

Diagnostic Value of Aspergillus IgG in ABPA

According to the 2024 revised ISHAM-ABPA working group consensus criteria, positive IgG against A. fumigatus is one of the "other components" for diagnosing ABPA, alongside the essential components of A. fumigatus-specific IgE and serum total IgE, with a recommended cut-off of ≥0.35 kUA·L−1 and ≥500 IU·mL−1 respectively 1, 3
A. fumigatus-specific IgG can be detected using lateral flow assays or enzyme immunoassays, with population-specific cut-offs recommended, such as ≥27 mgA·L−1 for certain populations and ≥40 mgA·L−1 for others 4

In the diagnostic algorithm for ABPA, elevated A. fumigatus-IgG or lateral flow assay is considered alongside A. fumigatus-specific IgE, serum total IgE, and blood eosinophil count 1, 5
A. fumigatus-specific IgG can be elevated in other conditions, including certain pulmonary diseases, requiring careful clinical correlation 2, 6

The British Thoracic Society guideline notes that immunoprecipitation techniques to detect Aspergillus-specific IgG antibodies have been largely replaced by ELISA, which has higher sensitivity compared to counter immuno-electrophoresis 7
There is a high probability of misclassifying ABPA if IgE and IgG against Aspergillus species are performed using non-standardized assays 1, 2