The role of tissue eosinophils after lung transplantation: back into business?

Eosinophils are granulocytes, developing in the bone marrow. Differentiation and survival of these cells is dependent on interleukin (IL)-5 through the IL5Rα. Their half-life in the blood is around 1.8 days and after migration to different organs, they contribute in remodeling, metabolic and microbiome homeostasis, and may act as sentinels for infection (especially parasitic), fibrosis and cancer. The role of the eosinophil is very well known in allergic asthma, which is driven by T helper 2 cells, secreting IL 4, 5 and 13 which leads to eosinophilic airways inflammation (3). In nonallergic eosinophilic asthma, on the other hand, type 2 innate lymphoid cells ( ILC2), are responsible for eosinophilic inflammation, again through the production of the same type 2 chemokines, however, with some steroid resistance of the eosinophil.