In the Lymph Node (IMAGE) University of Bonn Caption The microscopy photo shows the components of an important immune mechanism. The killer cells are shown in red, the helper cells are shown in blue and connective tissue cells are shown in gray. The platform on which the killer and helper cells meet is stained green. Credit (c) Source: Anna Brewitz/Kastenmueller laboratory Usage Restrictions This photo may be used with the press release. 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.