Screening and diagnosis of acute and chronic bird-related
hypersensitivity pneumonitis by serum IgG and IgA antibodies to bird
antigens with ImmunoCAP®
Background: Bird antigens are some of the most relevant antigens in
hypersensitivity pneumonitis (HP). Possible sources of bird antigens are
bird breeding, feather products and fertilizer with fowl droppings. For
the screening and diagnosis of HP, the measurement of bird-specific
antibodies should be standardized. Objective: The aim of this study was
to clarify the utility of serum IgG (sIgG) and serum IgA (sIgA)
antibodies to bird antigens in screening and diagnosing acute/chronic
bird-related HP with ImmunoCAP® in multi-centre clinical research.
Method: We performed a clinical performance test by conducting a
multi-institutional study to measure the levels of sIgG/sIgA against
pigeon, parrot and budgerigar antigens by the ImmunoCAP® system in 29
acute and 46 chronic bird-related HP patients. Results: The levels of
sIgG/sIgA against the bird antigens of the three species were
significantly higher in subjects with acute bird-related HP and chronic
bird-related HP with acute episodes (recurrent type) than in the control
subjects. For sIgG, the optimal cutoff values by ROC analysis were 24.6
mgA/L for pigeon, 14.0 mgA/L for parrot, and 8.7 mgA/L for budgerigar.
By measuring multiple bird antigens and combining sIgG values of two
species, the sensitivity and specificity for acute and recurrent-type
chronic bird-related HP patients were 85-91% and 73-80%, respectively.
For recurrent and insidious types of chronic bird-related HP, the
sensitivity and specificity were 48-61% and 73-80%, respectively.
Conclusion: The measurement of the levels of sIgG/sIgA against pigeon,
budgerigar and parrot antigens by ImmunoCAP® was useful for screening
and diagnosis in bird-related HP.