Marijuana Linked to Cancer, Disease Research on mice suggests pot can foil immune response By Evann Gastaldo, Newser Staff Posted Nov 25, 2010 8:56 AM CST Updated Nov 28, 2010 7:50 AM CST 116 comments Comments A marijuana user poses a joint over some ground marijuana Thursday, Nov. 4, 2010 in Tempe, Ariz. (AP Photo/Matt York) (Newser) – So much for legalization proponents who argue that marijuana is relatively harmless: New research suggests the drug actually increases your chances of getting cancer and other diseases. THC, the chemical that causes a marijuana high, also fuels production of cells that weaken the immune system, experiments on mice show. It is thought to increase vulnerability to pneumonia, bacterial infections, and tumors in the breast, bladder, lung, and elsewhere, the Daily Mail reports. THC triggered the production of myeloid-derived suppressor cells (MDSCs), immune cells that act as a brake to ensure the immune system doesn’t get out of control while battling disease. The “massive” number of MDSCs produced, however, appear to make it easier for tumors to grow or diseases to set in. On a positive note, the research suggests that marijuana could be useful in treating disorders where the immune system does need to be repressed. Thinking about getting a "legal high" instead? Click here to find out why you won't be able to for much longer.