Proteolytic activity of the house dust mite allergen Der p 1 enhances allergenicity in a mouse inhalation model.

We have recently demonstrated that intraperitoneal immunization of mice with proteolytically active Der p 1, the major house dust mite allergen, results in a significant and selective enhancement of total and Der p 1-specific IgE synthesis compared to mice immunized with proteolytically inactive Der p 1. To investigate whether the proteolytic activity of Der p 1 would lead to enhanced inflammatory cellular infiltration of the lungs and systemic IgE production when administered through the respiratory system, which is the natural route of entry for this allergen. Groups of mice were initially sensitized with proteolytically active Der p 1 through the intraperitoneal and the subcutaneous routes and subsequently exposed intranasally to either proteolytically active Der p 1, inactive Der p 1 or PBS. The extent of cellular infiltration of the lungs and systemic IgE production in the three animal groups were then compared. Here, we show for the first time that the administration of proteolytically active Der p 1 to mice through the intranasal route leads to significant inflammatory cellular infiltration of the lungs and systemic production of IgE. These data underline the important role of the proteolytic activity of Der p 1 in driving the allergic response in the lungs.