Natural Killer T-Cells Trigger Asthma

Researchers working with a mouse model for human asthma have found that asthma developed only when the animals had natural killer T-cells (NKT cells) in their lungs.

In a study published March 31, 2003, in the online edition of Nature Medicine, investigators at the Stanford University Medical Center (Stanford, CA, USA) described a series of experiments performed with a line of mice genetically engineered to lack NKT cells.

They found that exposing these mice to airborne antigens known to stimulate asthma failed to induce airway hyper-reactivity (AHR) despite the presence of type 2 T-helper (Th2) cells, which normally trigger mucous production and airway constriction. When the mice lacking NKT were injected with NKT cells, they responded to the airborne antigens by developing asthma similarly to control animals.

"We were quite surprised by the clarity with which the mice either got asthma or not depending on whether or not they had NKT cells,” said senior author Dr. Dale Umetsu, professor of pediatrics at the Stanford University School of Medicine. "Prior to these studies, one assumed that Th2 cells were all that was needed to induce asthma, and they do play a very important role in asthma pathogenesis. Now it is clear that even if you have Th2 cells but you do not have NKT cells, you do not get asthma.”

The essential role of the NKT cells makes them logical targets for asthma therapy. "We are starting to look at people to see how these NKT cells may affect the development of asthma,” said Dr. Umetsu. " If we can find specific surface markers, we may be able to direct therapies specifically against the NKT cells to eliminate them.”



Related Links:
Stanford University Medical Center