ICOS and Autoimmunity: The lack of spontaneous inflammation or autoimmunity in Ikzf1-fl-Foxp3-Cre mice is similar to mice with Treg-specific deletion of Prdm1 (Bankoti et al., 2017; Cretney et al., 2018), Icos (Guo et al., 2008), Il10 (Rubtsov et al., 2008) and Mef2d (Di Giorgio et al., 2020).