Helper cells aid asthma fight – study

Flu-triggered asthma attacks could be controlled by targeting a set of newly-recognised immune cells, a study suggests.

Asthmatic children who contract flu frequently end up in hospital fighting for breath.

But the reason for the severity of asthma attacks brought on by flu and other infections has not been clear.

A mouse study in the US has now pointed to an explanation. Scientists believe the trigger mechanism involves natural helper cells, a recently discovered element of the immune system.

Natural helper cells were first found in the gut, where they protect against parasitic worm infections.

“Since the lung is related to the gut – both are exposed to the environment – we asked if natural helper cells might also be in the lung and be important in asthma,” said lead researcher Dale Umetsu, from the Children’s Hospital Boston.

Tests showed that the cells did exist in the lungs of asthmatic mice with influenza.

The virus stimulated production of an immune system signalling molecules that activated natural helper cells. These in turn secreted chemicals that triggered asthma attacks.

“Without these cells being activated, infection did not cause airway hyper-reactivity, the cardinal feature of asthma,” said Dr Umetsu.