More than 600,000 Kiwis with asthma could soon be breathing easily.
Scientists in the US have found a way to stop the body's immune system from attacking allergens, by tricking it into thinking they're harmless particles.
The breakthrough is being spoken of as a "cure" not just for asthma, but food allergies and hay fever.
A biodegradable nanoparticle encases the allergen, effectively hiding it from the immune system's Th2 cells -- whose overreaction causes the allergy. The hidden allergens are then swept up by specialist cleaning cells.
"The vacuum-cleaner cell presents the allergen or antigen to the immune system in a way that says, 'No worries, this belongs here,'" says Stephen Miller of Northwestern University, who led the research.
"The immune system then shuts down its attack on the allergen, and the immune system is reset to normal."
So far the technique has only been tested on mice, but the "technology is progressing quickly" and human trials are being planned.
While the mice were bred to show asthma-like symptoms when exposed to egg protein, scientists say the technique could be used on anything that causes an allergic reaction.
"Depending on what allergy you want to eliminate, you can load up the nanoparticle with ragweed pollen or a peanut protein," says Prof Miller.
"The findings represent a novel, safe and effective long-term way to treat and potentially 'cure' patients with life-threatening respiratory and food allergies. This may eliminate the need for life-long use of medications to treat lung allergy."
The treatment also encourages the immune system to make more regulatory T cells, which are "important for recognising the airway allergens as normal".
New Zealand has one of the highest rates of asthma in the world.