Pamidronate is a bisphosphonate drug that has been used for the treatment of osteoporosis and Paget’s disease. The medication works in bones to inhibit osteoclasts, which accelerate the breakdown of bone. Researchers from the University of Hong Kong have discovered a new use for this medication in the treatment of influenza. The researchers found that pamidronate activates a type of white blood cell known as gamma delta T cells. By causing increased activation of this subset of white blood cells with pamidronate, the researchers have boosted the immune system’s response to influenza. White blood cells that are infected with the influenza virus are attacked by this subset of T cells. This is a novel method to treat influenza because instead of targeting the influenza virus with antiviral medications, this method instead strengthens the bodies’ response to the infection. The researchers used “humanized” mice that carried a complete set of human white blood cells. The mice were infected with either the notorious H1N1 swine flu virus, the H5N1 bird flu virus, or the H9N2 bird flu virus. For all three groups, the mice that were treated with pamidronate recovered from the influenza infection while the mice that were not treated died within a few days. Interestingly, mice that were engineered to lack the gamma-delta subset of T cells did not benefit from treatment with pamidronate. This finding shows that pamidronate specifically targets gamma-delta T cells for activation but does not stimulate their production. Pamidronate may serve a role in the treatment of influenza pandemics when there is not enough time to develop a vaccine. In addition, pamidronate is not subject to the development of resistance because the drug does not target the influenza virus but instead boosts the immune response to the virus. Future studies will focus on developing human clinical trials to test the utility of pamidronate in humans.
Wenwei Tu et al. “The aminobisphosphonate pamidronate controls influenza pathogenesis by expanding a gamma-delta T cell population in humanized mice” Journal of Experimental Medicine published online June 27, 2011