To investigate a possible role of CD4+CD25+FoxP3+CD127lo Treg in the immune system in B-cell NHL, both peripheral tolerance and the tumor microenvironment, we measured the frequencies of CD4+CD25+FoxP3+CD127lo Treg in PB, BM and involved lymphatic tissues from patients with B-cell NHL. This evidence concerns the gene FOXP3 and B-cell non-Hodgkin lymphoma.