ABPA is a disease state induced by an arthus reaction to colonising aspergillus in the bronchi of patients with bronchial asthma . It is characterized by Type I and Type III Gel-Coombs reactions to the aspergillus antigen .

Some of the laboratory characteristics observed are circulating IgE and IgG specific antibodies against A.fumigatus (a fungus ). Aspergillus-precipitating antibody is also detected in blood serum. IgE levels and eosinophiles are elevated.

ABPA responds to systemic steroids .