D1.72 - Comparison of the allergenic composition of available SPTs for the diagnosis of sensitization to D. pteronyssinus

Dermatophagoides pteronyssinus is a major source of indoor allergens, with Der p 1, Der p 2, and Der p 23 being the clinically relevant components. Skin prick test (SPT) is essential for allergic diagnosis. However, the allergenic composition of commercial extracts varies between manufacturers, potentially affecting diagnostic accuracy and may impact in clinical decisions.

This study compares the allergenic profiles of different D. pteronyssinus extracts and molecular allergens used in SPT. The results will assess variability of Der p 1, Der p 2, and Der p 23 among SPT availables.

The content of major allergens in 4 complete extract D. pteronyssinus (SPT-A-D) and the purified molecular allergens (SPT-E-G) was studied by specific quantification of Der p 1, Der p 2 and Der p 23 by ELISA and western blotting with specific antibodies. The protein profile was compared by SDS-PAGE.

Bands in protein profile corresponding to Der p 1, Der p 2 and Der p 23 were verified by Western blotting. In the quantification, the values of all the allergens are low in SPT-A, moderate in SPT-B and highest in SPT-D. Both SPT-C and D have sufficient amounts of Der p 1, even higher than purified SPT-E, however only SPT-D has sufficient amounts of Der p 2, although lower than purified SPT-F. All the total extract SPTs (A to D) have quantities of Der p 23 lower than 0.8 µg/mL, being much lower than the quantity of SPT-G which reaches 2.5 µg/mL.

Variability in protein profiles and concentration in mayor allergens in commercial SPT may influence the test sensitivity. This variability is evident in Der p 2 and Der p 23, as Der p 1 is guaranteed in all products except one. The amount of Der p 23 is worryingly low in the full extract SPTs, however the purified SPTs have the right amount of the three components separately.