This is the time of year when many of us are stocking up on antihistamines and other allergy treatments, and a new study finds that those antihistamines may also be useful in fighting cancer.
The study by researchers and Virginia Commonwealth University demonstrated that histamine, a component of the immune system that responds to allergens and foreign pathogens and is also linked to inflammation, plays a role in protecting tumors from the immune system.
By blocking the production of histamine in animal models, the researchers were able to interrupt a process that promotes melanoma growth.
"This research is very exciting as it draws a connection between two diseases that aren't commonly linked: allergy and cancer," said VCU School of Medicine professor Daniel H. Conrad, Ph.D. "However, it's important to realize that this connection is very novel and further research is needed before we know if antihistamines can be used effectively in cancer therapies."
Histamine is produced by mast cells, which are especially numerous in the nose, mouth and blood vessels to help defend against pathogens and aid in wound healing. The researchers found that histamine induces proliferation of cells called MDSCs, which help promote tumor growth by suppressing the immune system. They also discovered that MDSCs tend to migrate toward mast cells, which help traffic the MDSCs to sites of inflammation such as the liver and tumors.
Through their experiments, the researchers showed that MDSCs can be decreased by over-the-counter antihistamines such as cetirizine (Zyrtec) and cimetidine (Tagamet).
In addition, the researchers found that patients experiencing allergic symptoms have more MDSCs circulating in their bloodstream than non-allergic patients.
"MDSCs have generated a great deal of interest in recent years because they limit the effects of the immune response against cancer," says study collaborator Harry D. Bear, M.D., Ph.D. "Now that we have shown that antihistamines can interfere with the production of MDSCs, we are hopeful that we may be able to use them to restore the immune system's ability to fight off tumors."
The study was recently published in the Journal of Leukocyte Biology.