Regulatory T cells in cancer

Increasing evidence supports the existence of elevated numbers of regulatory T cells (T(reg) cells) in solid tumors and hematologic malignancies. Whereas the biology of CD4(+)CD25(+)FOXP3(+) T(reg) cells in murine models seems to be rather straightforward, studies in human diseases are more difficult to interpret due to expression of CD25 on activated effector T cells as well as T(reg) cells. More importantly, early studies in human tumors were mainly focused on CD4(+)CD25(+) T(reg) cells lacking interrogation of more specific markers such as FOXP3 expression. Although the increase of T(reg) cells seems to be a characteristic feature in most tumors, little is known about the molecular and cellular mechanisms…