show Abstracthide AbstractA majority of effector Treg cells (eTregs) that are abundant in many types of tumors are marked by the expression of Blimp1. However, the specific impact of Blimp1+ eTregs on, and mechanisms of action within, tumors remain unknown. To better understand the role of Blimp1 in the regulation of eTreg function in the tumor immunity, we profiled the differential gene expression in Blimp1-deficient eTregs compared to WT control eTregs from tumor-bearing mice. Overall design: Prdm1fl/flFoxP3YFP-Cre (KO) and FoxP3YFP-Cre (WT) mice were subcutaneously inoculated with B16.OVA at day 0, and intraperitoneally immunized with NP-OVA in CFA at day 0 and NP-OVA in IFA at day 7. When the tumor reached = 1.5 cm3, CD45+CD44+YFP+(FoxP3+)CD4+CD3+ Tregs were FACS-sorted from spleens and tumors of these mice. RNA was prepared and sequencing was performed at Genewiz (South Plainfield, NJ) using Ultra-Low Input RNA-Seq Service.