US scientists have found a new way to fight cancer tumors that suppress anti-tumor immune cells in close proximity to the affected tissue.
It turned out that large secretory cells (Clara cells) secrete anti-immunosuppressive factors that suppress tumor cells, Nature Cancer reported.
Researchers have identified a set of anti-immunosuppressive factors that can be secreted by Clara cells that line the airways in the lungs. These factors inhibit potent immunosuppressive cells called myeloid suppressor cells (MDSCs), which help tumors avoid an anti-tumor immune response.
Inhibition of MDSC led to an increase in the number of antitumor T cells at the tumor site and significantly increased the effectiveness of immunotherapy with immunoglobulin PD1. Using a mouse model of non-small cell lung cancer, the most common form of lung cancer, scientists have found for the first time that this effect peaks with a moderate dose of radiation, and the number of mice surviving quadrupled to 40 percent. Radiation causes large secretory cells to produce anti-immunosuppressive factors.
The study authors found that it is possible to replace radiation with a cocktail of eight such factors and get the same anti-immunosuppressive effect. Scientists are now looking to determine which molecules are most important for inhibiting MDSC and increasing the effectiveness of cancer treatments.