About the Cover
Regulatory T cells contribute to the protumor environment in cancer. Large numbers in tumors, or a high regulatory T:CD8⁺ T cell ratio, is associated with a poor prognosis. However, that relationship is not always found in urinary bladder cancer. Winerdal et al. first established that the regulatory T cells in human bladder cancers are functionally suppressive like other regulatory T cells. They then observed that these regulatory T cells suppressed tumor and macrophage production of MMP2, a metalloproteinase that aids metastasis. Thus, higher numbers of regulatory T cells congregating at the invasive front of a tumor correlated with survival. Read more in this issue on page 528. Original micrograph from the Winqvist laboratory shows a bladder tumor infiltrated and surrounded by brown T cells, some of which are regulatory. Artwork by Lewis Long.