Blocking a powerful immune system chemical could provide a new treatment for patients suffering from severe asthma, scientists said on Thursday.Asthma affects about 150 million people worldwide. About one in 10 sufferers has a severe form of the illness.Professor Stephen Holgate, of Southampton General Hospital in southern England, and his team said patients with severe asthma had higher levels of a chemical called tumour necrosis factor alpha (TNF alpha) than other sufferers.In a study of about 150 people, the researchers found that blocking the production of TNF alpha with a drug produced a significant improvement in symptoms and lung function.
