Nevertheless, our finding that ILC2-derived LIF is a previously unappreciated regulator of immune cell trafficking raises fundamental questions about the role of this cytokine in human allergic disease and infections, but also in a broad range of other diseases—for example, inflammatory bowel disease and cancer in which intratumoural TLS54 correlate with low LIF expression and may represent a positive prognostic indicator for certain cancers55. This evidence concerns the gene LIF and infection.