Under normal circumstances, regulatory T cells inhibit the immune system from attacking its own cells and tissues to prevent autoimmune diseases, said Dr. Si-Yi Chen, a professor of immunology and molecular microbiology who led the study at the University of Southern California. "Cancer cells take advantage of regulatory T cells' suppressor ability, recruiting them to keep the immune system at bay or disabling the immune system's attack provoked by tumor vaccines.

"Our study provides a new vaccination strategy to overcome the regulatory T cells' immune suppression, while avoiding non-specific overactivation of autoreactive T cells and pathological autoimmune toxicities."

The study identified a new molecular enzyme called A20 that restricts inflammatory signal transduction in dendritic cells.

"Through a series of immunological studies, we have identified A20 as an essential antigen presentation attenuator that prevents the overactivation and excessive inflammation of the dendritic cells, which, in turn, restricts the potency of tumor vaccines," said Chen.

The study that included Xiao-Tong Song, Kevin Kabler, Lei Shen, Lisa Rollins and Xue Huang appears in the journal Nature Medicine.