London, Mar 3 : Researchers at the University of Southern California (USC) have revealed that turning off the suppression function of regulatory T cells may lead to a new way to develop more effective tumour vaccines.
The researchers have discovered an enzyme called A20 that can prevent over activation of the regulatory T cells thereby stimulating strong immune responses.
"Under normal circumstances, regulatory T cells inhibit the immune system to attack its own cells and tissues to prevent autoimmune diseases," Nature Medicine quoted Dr Si-Yi Chen, professor of immunology and molecular microbiology at the USC/Norris Comprehensive Cancer Centre and the Keck School of Medicine of USC, as saying.
"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 tumour 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," Chen added.
Dendritic cells are the immune cells that trigger immune responses to recognize and wipe out tumour cells.
The study conducted using a mice model showed that A 20 inhibited the transduction of dendritic cells. Consequently, the cells over produced a group of cytokines and co-stimulatory molecules that generated strong immune responses, which cannot be suppressed by regulatory T 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 tumour vaccines," said Chen.
The researchers believe that these findings will allow new generation of tumour vaccines to be developed.
The study appears in Nature Medicine.