A mechanism by which tumor cells are able to stay one step ahead of the immune response is revealed in a report published online in Nature Immunology this week.
Masahisa Jinushi and colleagues looked at dendritic cells (DCs) associated with tumors and found that they possess high amounts of a molecule called Tim-3. DCs normally play important roles in activating immune responses and are thereby involved in destroying tumors; however the authors note that when they express Tim-3, the DCs instead dampen immune responses. Chemotherapeutic drugs can work in conjunction with the immune system by killing tumor cells which then release their DNA to activate DCs and trigger an anti-tumor response. However, Tim-3 is able to bind immunostimulatory DNA, sequester it and thereby prevent DCs from becoming activated. The team found that preventing DC-associated Tim-3 from binding DNA boosted anti-tumor responses in a mouse model of cancer.
This study suggests new avenues by which effective immune responses in cancer might be generated.