Safety of segmental allergen challenge in human allergic asthma

Background: Segmental allergen challenge is widely used to study mechanisms of human allergic asthma. Despite the relatively large dissemination, limited information is available about the safety of this method. Objective: Observational, retrospective study to report the adverse events of segmental allergen challenge in a large group of volunteers with asthma. Methods: In total, 78 cases from several studies performed between 1994 and 2007 were pooled for this analysis. Volunteers underwent allergen challenge using either a fixed dose of allergen (7 cases) or an individually standardized allergen dose defined by an inhaled allergen test before the challenge (71 cases). A subgroup of 13 volunteers underwent repeated challenges, with more than 6 months between the challenges. Results: With a fixed dose instilled during bronchoscopy, 43% of the participants developed wheezing and coughing, requiring 2-6 puffs of a beta(2)-agonist after segmental allergen challenge. In volunteers with individually standardized doses, a beta(2)-agonist was required in only 19% of the cases. No severe adverse events occurred in all cases studied. Volunteers who underwent repeated challenges did not develop more adverse events than those who underwent 1 challenge. Conclusions: Segmental allergen challenge is a safe tool to study the mechanisms of human allergic asthma, even when repeated challenges are performed in the same patient. It is associated with only a few, tolerable adverse events, especially when the dose of allergen is standardized individually.