A new immune-response cell type found in the lung has an important role in virus-induced asthma, reports a study published online this week in Nature Immunology. The identification of these cells in the lung and the molecules involved in their activation and function should provide new targets for the control of asthma exacerbated by viral infection.
Asthma, a chronic disease of the airways, can often be triggered by influenza infection. It is classically thought to be caused by inappropriate activation of an ‘adaptive’ immune response composed of T cells and B cells of the immune response, which have unique antigen receptors for recognizing foreign elements and retain memory for such recognition. ‘Innate’ immune responses, on the other hand, are composed of various nonspecific cells of the immune system and have not been linked to asthma.
Dale Umetsu and colleagues have identified a cell of the innate immune response that resides in the lung and has an important role in influenza-induced asthma. These so-called ‘natural helper cells’ respond to molecular triggers released by lung cells after influenza infection and drive asthma symptoms in a completely T cell- and B cell-independent manner.