A PRECEDING AIRWAY REACTION TO ONE ALLERGEN MAY LEAD TO PRIMING OF THE AIRWAY RESPONSES TO ANOTHER ALLERGEN

This study aimed to determine whether a preceding airway response to o ne allergen leads to priming of the airway responses to another allerg en. Twelve asthmatic children who had positive prick tests to two alle rgens, Dermatophagoides pteronyssinus (D.p.) and German cockroach (CR) , participated in a randomized, placebo-controlled crossover study. We performed two consecutive inhalation challenges, D.p. challenge being followed 48 h later by CR challenge. The effect of initial (D.p.) cha llenge on the early and late airway responses to the subsequent (CR) c hallenge (CR2) was examined by comparing the responses with those to C R challenge preceded by sham challenge (CR1). The geometric mean PD20 of CR allergen in the CR2 was 2.8 BU (breath unit) (range of 1 SD; 0.7 7-10.4), which was 12.0-fold less than that (33.7 BU, 10.8-105.2) in t he CR1. The administration of a 6.1-fold less dose (8.9 BU, 2.7-28.8) in the CR2 than in the CR1 (54.5 BU, 44.1-69.3) provoked a similar deg ree of late-phase reactions (18.7 +/- 7.3% vs 15.8 +/- 9.6%). Our data indicated that the early- and late-phase reactions to CR challenge we re augmented by the preceding reaction to D.p. This suggests that a pr eceding airway response to one allergen may lead to priming, with enha ncement of the early and late airway responses to the subsequent chall enge with another allergen.