Ten years ago, the cloning and sequencing of a cDNA encoding the group I al
lergen of house-dust mites unequivocally determined that protein allergens
may have biochemical functions in addition to their ability to bind IgE. Si
nce this discovery, several groups have speculated that the biochemical act
ivities of allergens, or substances associated with allergens, may be invol
ved in their immunogenicity or allergenicity. This paper will focus on just
one biochemical function, proteolytic activity, and will be illustrated by
examples of our own work that we believe support the hypothesis that this
category of molecules are endowed with the properties of proallergic adjuva
nts.