IL9 and infection: Human CD4+ T cells that commit to a TH1 or TH17 fate or that produce IL-9 have important roles in host defense against different infections, particularly those caused by fungal and staphylococcal species (Badolati et al., 2023; Bröker et al., 2016; Brown et al., 2015; McDonald, 2012; Puel et al., 2012; van de Veerdonk and Netea, 2010; Zielinski et al., 2012).