Asthma linked to toxins from white blood cells

A type of white blood cell has been identified as being directly responsible for the development of asthma.

A type of white blood cell has been identified as being directly responsible for the development of asthma.

The cells, called eosinophils, have often been found in the lungs of people with asthma. Two American studies provide new evidence to show that eosinophils are closely involved in the disease.

By breeding mice without the cells, scientists were able to show that substances which triggered an asthmatic reaction in normal mice had no effect on the mice which lacked eosinophils - a finding which could help in developing treatments for the condition.

The work published today in the journal Sciencecontradicts a study published in 2000 in the medical journal The Lancet, which concluded that eosinophils do not have a significant role in the development of asthma in humans.

Eosinophils are a type of white blood cell found in animals whose natural role appears to be to protect us against parasites, by congregating around them and releasing deadly toxins. In an asthma attack, those toxins are released inappropriately - leading to damage of the lung, nose and throat tissues.

"The new studies clearly show evidence that eosinophils have a role in asthma," said Dr Marsha Wills-Karp, chair of the division of immunobiology at Cincinnati Children's Hospital Medical Centre, who commented on the studies for Science. "If these cells turn out to be important, they will be good drug targets."