In addition, as chitin is a major component of the insect exoskeleton, our findings may have relevance to known asthma-associated allergens such as cockroach and house dust mite, in that inflammation-driven responses to AHR during chronic exposure to cockroach or house dust mite extracts may be provoked by both chitin and other allergens in these preparations [e.g., the Der p1 cysteine proteinase from house dust mite (36)]. This evidence concerns the gene AHR and asthma.