Anti-Mouse FOXP3-BX024; Alexa Fluor™ 647-RX024 (F400-25Tests)

FOXP3 is a transcription factor1 required for development of CD4+CD25+ regulatory T cells (Treg) that does not affect CD4+CD25− T cell proliferation2. Treg cells expressing FOXP3 play a critical role in the maintenance of immune homeostasis and prevention of autoimmunity1. FOXP3 promotes the generation of Tregs, represses cytokine expression in primary CD4+ T cells, and suppresses the transcriptional activities of NFAT and NF-κB3. FOXP3 also inhibits basal activation of PKC-θ, IκB kinase β (IKKβ), and TNF-α stimulation of NF-κB. Depletion of FOXP3+CD4+ Treg cells and/or loss of function mutations of FOXP3 results in severe autoimmunity, allergy, immunopathology as well as cancer immunity1. FOXP3 is predominantly expressed in CD25+CD4+ Tregs in the thymus and periphery2,4, and abundance increases upon in vitro activation of CD4+CD25+ Tregs2. Additionally, expression of FOXP3 in naïve T cells can convert these cells to a Treg phenotype4. FOXP3 is virtually undetectable in resting and activated CD4+CD25− T cells2. FOXP3 represents a more specific marker for CD4+ Tregs than e.g., CD25, CD45RB, CTLA-4, and GITR which do not discriminate between Tregs and activated, effector, or memory T cells4.