One of the key roles of the immune system is the capability to distinguish self from non-self. Whilst recognition of foreign antigens is vital for immune responses to pathogens, the failure to recognize self antigens can cause autoimmune diseases.
Over a decade ago scientists discovered a population of suppressive CD4+ T cells expressing CD25. It seemed that these cells were capable of preventing autoimmune disease. This regulatory T cell population, commonly known as Tregs, suppresses T cell proliferation and cytokine production, thus providing protection from autoimmunity, transplant rejection1, graft-versus-host disease, allergy2 and tissue damage during infection. Conversely, Tregs can also enable tumor cells to evade the host immune response3.
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Currently, the best single Treg marker is the forkhead transcription factor FOXP3. Subsequent genetic studies have confirmed that FOXP3 plays a key role in both Treg development and function. FOXP3 is a nuclear protein requiring cell fixation and permeabilization for detection by flow cytometry - Leucoperm™ cell permeabilization reagent, product code BUF09, is recommended for this purpose. Therefore, while FOXP3 is an important lineage marker it does not facilitate Treg purification for functional studies.
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The constitutive expression of CD25 is characteristic of Treg cells. Regulatory activity is enhanced in those CD4+ T cells expressing the highest levels of CD25 (CD4+CD25hi cells), however, activated T cells up-regulate CD25 during immune responses associated with infection, which causes difficulties in discriminating between Treg and activated T effector cells. Thus, Treg identification is often achieved using multiple markers, including GITR and CTLA-4; Treg cells express intra-cytoplasmic and cell-surface CTLA-4 (CD152), which is a negative regulator of cell-mediated immunity, and GITR (Glucocorticoid-induced Tumor necrosis factor receptor family-Related)3. Other popular markers include CD45RB, CD62L, CD103 and LAG-3.
AbD Serotec stocks a wide range of antibodies to human, mouse and rat Treg markers and related molecules. The Low Endotoxin formats have been optimized for functional studies and contain < 10 EU/mg endotoxin, the lowest commercially available. All reagents are guaranteed to work in the applications stated.
Download our Tregs Factsheet for an overview of our rodent and human markers!
References:
1) Walsh, P.T et al (2004) J. Clin. Inv. 114(10):1398-1403
2) Robinson, D.S et al(2004) J. Clin. Inv. 114(10):1389-1397
3) Casares, N et al (2007) Immunologia 26(1):29-41
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