Lungs (IMAGE) Salk Institute Caption In lungs lacking a 'halt' signal from regulatory T cells, (right) killer T cells and other pathogen fighters accumulate (purple rings) in an excessive immune system response, creating lung inflammation and asthma-like symptoms. Credit Salk Institute for Biological Studies Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.