Comment on Review article by Kristina Johansson and Henry McSorley entitled “Interleukin‐33 in the developing lung – Roles in asthma and infection.”

In their important review, Johansson and McSorley highlight the features of an upstream epithelial cytokine, IL-33, with instructive roles in TH2 inflammation (1). Emanating from stressed epithelium, IL-33 now attracts major interest as a player in adult asthma including viral infection-evoked exacerbations. However, I find the authors' discussion of potential involvement of IL-33 in development of asthma in infants in association with RSV infection particularly intriguing.