B6 (C57BL/6), Rag1−/− and CD45.1, Rosatdtomato,Vav1cre, Cd2cre, Rorccre and RorcGFP/+ mice were all obtained from The Jackson Lab. M-NSG (NOD-PrkdcscidIl2rgem1/Smoc) mice were purchased from Shanghai Model Organisms Center, Inc. Bcl6ERT2cre mice were generated by Biocytogen, Co., Ltd. Briefly, P2A-iCreERT2 was inserted before the stop codon of Bcl6 gene to generate Bcl6ERT2cre mice. Bcl6RFP/RFP, Bcl6fl/fl mice were generated by our lab and described in previous studies (Liu et al., 2016 (link)). B6 mice were crossed with CD45.1 mice to generate CD45.2+CD45.1+ congenic mice. Bcl6RFP/RFP mice were crossed with RorcGFP/+ mice to generate double report mice. Vav1cre, Cd2cre, and Rorccre mice were crossed with Bcl6fl/fl mice to generate various conditional knockout mice. All these mice were bred and maintained in the SPF animal facility at Tsinghua University. All animal experiments were performed according to the governmental and institutional guidelines for animal welfare and approved by the Institutional Animal Care and Use Committee, Tsinghua University.