GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE262nnn/GSE262925/primaryOK200TranscriptomicsMus musculusExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE262925GEOGSEfalseAn IL-21-expressing effector CD8+ T cell subset provides superior control of infection and cancerCD8+ T cells are critical in immune responses against pathogens and malignancies. After activation, antigen-specific CD8+ T cells differentiate into cytotoxic effector cells, which are regarded to be phenotypically similar and unlike CD4+ T cells, do not contain different functional subsets. Interleukin 21 (IL-21), well known to be primarily produced by CD4+ T cells, exerts multifaceted effects on the regulation and function of CD8+ T cells. In this study, utilizing IL-21 reporter and fate-mapping mice, we have uncovered a new population of IL-21-expressing CD8+ T cells in the context of infection and cancer. These T cells, coined as Tc21 cells, exhibited remarkable proliferative and cytotoxic capacities, with elevated expression levels of IFNγ and GZMB, than IL-21- T cells. Tc21 cells efficiently developed into memory cells during acute infections and maintained a less dysfunctional state in chronic infection. Importantly, Tc21 cells played a pivotal role in mounting effective protection to virus and cancer. Collectively, these findings highlight an effector subset of IL-21-expressing CD8+ T cells pivotal in host protection, and may suggest new approaches of cancer immunotherapy.2026/08/01GSE262925GSM8181549GSM8181548GSM8181559GSM8181558GSM8181557GSM8181567GSM8181556GSM8181566GSM8181555GSM8181565GSM8181554GSM8181564GSM8181553GSM8181552GSM8181563GSM8181551GSM8181562GSM8181561GSM8181550GSM818156021103262925Mus musculus