Rela flox/flox, H11LSL-Cas9, and Cd4cre mice were obtained from The Jackson Laboratory. Relb−/−, OX40L-Tg, and Foxp3gfp reporter mice have been previously described (Xiao et al., 2012a (link)). Some strains were crossed with Foxp3gfp mice to genetically mark Foxp3+ T regulatory cells for cell sorting purposes. All animals were maintained in a specific pathogen-free facility at Houston Methodist Research Institute in Houston, TX. Animal use and care were approved by the Houston Methodist Animal Care Committee in accordance with institutional animal care and use guidelines.