Antihistamines, which help reduce watery eyes and runny noses during allergy season, might also help ward off tumors too. A new report suggests that antihistamines may have significant anti-cancer properties as they interfere with the function of a type of cell that is known to reduce the body's ability to fight tumors - myeloid derived suppressor cells.

To make this discovery, researchers examined two groups of mice that involve myeloid derived suppressor cells. The first group of mice was infected with a rodent intestinal helminth to simulate a strong allergic response. Then they were injected with myeloid derived suppressor cells and treated with anti-histamines, cetirizine or cimetidine. Treatment with these anti-histamines reversed the effects of myeloid derived suppressor cells.

The second group of mice had tumors and were injected with myeloid derived suppressor cells and treated with the antihistamine, cimetidine. In this group, the antihistamine also reversed the enhanced tumor growth normally seen with myeloid derived suppressor cell injection.

Finally, the scientists examined blood from patients with allergy symptoms (typically associated with increased histamine release). The scientists found that these patients had increased circulating myeloid derived suppressor cells over non-allergic controls. 

 "This research is very exciting as it draws a connection between two diseases that aren't commonly linked: allergy and cancer," said Daniel H. Conrad, Ph.D.,of Virginia Commonwealth University in Richmond. "It's important to realize, however, that this connection is very novel and more research is needed before we know if antihistamines can be used effectively in cancer therapies."