Household dust may be more allergenic than previously thought — it can activate an innate immune defence.

Anthony Horner at the University of California, San Diego, Mitchell Kronenberg at the La Jolla Institute for Allergy and Immunology in California and their colleagues collected dust samples by vacuuming carpet in various homes. They added the dust to cultures of mouse and human immune cells called invariant natural killer T cells, which quickly recognize and respond to antigens. The researchers found that, in response to the dust, the cells churned out immune-signalling molecules called cytokines.

In a mouse model of allergy, exposing the rodents to house dust and an allergen resulted in more lung inflammation and a stronger immune response than did exposure to the allergen alone.

J. Exp. Med. doi:10.1084/jem.20102229 (2011)