A new type of human immune cell that exists in gut and lung tissues that contribute to the severity of asthma and allergic responses is identified in a paper online this week in Nature Immunology.
Previously, mice were found to have innate helper immune cells that secrete substances that elicit mucous production and recruit blood cells known as eosinophils. Both these immune responses lead to parasite elimination but also trigger allergy symptoms. Hergen Spits and colleagues asked if humans also have such cells. They identify a population of human innate cells that express the cell markers CRTH2, CD127 and CD161, which distinguish these cells from others in the lung and gut. Like the mouse cells, activated innate CRTH2+ cells elicit allergic types of immune reactions. Patients with a nasal infection, known as chronic rhinosinusitis, have higher numbers of the CRTH2+ cells.
It is not yet clear how this new subset of human CRTH2+ cells arises, but future work is needed to understand how to tame them to lessen chronic allergic responses.