The cysteine protease activity of the major dust mite allergen Der p 1 selectively enhances the immunoglobulin E antibody response

The house dust mite Dermatophagoides pteronyssinus allergen Der p 1 is the most immunodominant allergen involved in the expression of dust mite-specif ic immunoglobulin (Ig)E-mediated hypersensitivity. The reason for this pote nt IgE-eliciting property of Der p 1 remains unknown, but there is mounting in vitro evidence linking the allergenicity of Der p 1 to its cysteine pro tease activity. Here we demonstrate for the first time that immunization of mice with proteolytically active Der p 1 results in a significant enhancem ent in total IgE and Der p 1-specific IgE synthesis compared with animals i mmunized with Der p 1 that was irreversibly blocked with the cysteine prote ase inhibitor E-64. We conclude that the proteolytic activity of Der p 1 is a major contributor to its allergenicity.