Researchers in Berlin, Germany have found that a specific type of immune cell, the regulatory T lymphocyte (Treg) plays an important role in hypertension-induced cardiac damage. The injected Treg that they harvested from donor mice into recipient mice were infused with angiotensin II, a blood pressure-raising peptide. The Tregs had no influence on the blood pressure response to angiotensin II. Nonetheless, cardiac enlargement, fibrosis, and inflammation was sharply reduced by Treg treatment. Furthermore, the tendency to develop abnormal heart rhythms that could lead to sudden cardiac death was also reduced. Dr. Heda Kvakan and Dr. Dominik N. MÃøller at the Experimental and Clinical Research Center at the Max DelbrÃøck Center do not intend Treg as a therapy. However, a better understanding of how the immune system fits into hypertension-induced organ damage could result from these studies (Circulation, Vol. 119, No. 22, June 9, 2009, 2904-2912 ).*