Singapore - Two cell types work together to protect pancreatic tumors from destruction by the immune system. But, blocking this partnership may restore the system's ability to attack these same tumor cells. 

These are the findings of a study in mice led by researchers from NYU Langone Medical Center and its Perlmutter Cancer Center, and published online July 18 in Cell Reports.

The study results revolve around the immune system, which is designed to attack invaders like viruses. Immune cells also recognize cancer cells as abnormal, but such cells can turn off immune responses.

The current study found that Tregs have their effect by keeping a second cell type, dendritic cells, from activating a third cell type, CD8⁺ T cells, which would otherwise kill cancer cells.

"Our results argue that blocking the partnership between Tregs and dendritic cells might be needed to achieve effective immunotherapy for pancreatic cancer," says lead author Dafna Bar-Sagi, PhD, vice dean for science and chief scientific officer at NYU Langone. "Upcoming studies in our lab will be looking to confirm that this relationship can become the foundation of new treatment strategies." 

The study focused on pancreatic ductal adenocarcinoma (PDA), a lethal form of cancer known to come with an influx of immune cells into tumors. Past studies have linked this early Treg build-up in tumors with reduced survival.

The research team suggests that this normal contact between the two cell types is exploited by cancer cells, in which contact-based, mutually reinforcing cross-talk between them turns off the immune response. The same results suggest the Tregs and killer T cells may in fact compete for dendritic cells near tumors, say the authors.