Regulatory T-cells (Treg) play an essential role in the control of immune responses to self and foreign antigens maintaining the balance between immunity and tolerance. The nuclear forkhead box transcription factor gene FoxP3 appears to function as a master regulator in the development and function of Treg cells and has become a key identifier of these cells. The methods available to stain FoxP3+ cells are cumbersome and show variability depending on the clone of anti-FoxP3 antibody, the staining buffer composition and fluorochrome used. Therefore, an accurate, robust and simple Treg FoxP3 staining protocol using whole blood is a need for any research laboratory and to perform large scale research screening.
Our R&D team has observed that the FoxP3 signal obtained using the standard PerFix-nc protocol with the recommended optional wash was equivalent to other currently used procedures. Most importantly, we found that minor modifications can significantly improve FoxP3 staining.