Table 1. Important House Dust Mite (D. pteronyssinus) Allergens.

Tier	Denomination	Structure/function
Major*	Der p 1	Cysteine protease
	Der p 2	ML-domain lipid binding protein
Mid Tier**	Der p 4	α-Amylase
	Der p 5	Protein of unknown function comprised of a bundle of coiled coils
	Der p 7	LPS binding bactericidal permeability increasing protein (LBP/BPI)
	Der p 21	Paralogue of Der p 5

^* Major allergens Der p 1 and 2 collectively bind 50–60% of anti-HDM IgE antibody of HDM allergic subjects. ** Mid-tier allergens Der p 4,5,7 and 21 each bind IgE in 50% of HDM allergic subjects and collectively account for ca 30% of anti-HDM IgE antibody