By using a strain of mice that mimics many of the features of the human immune system and can be infected with the most common human form of the malaria parasite a team of scientists has identified a key host defense mechanism. Over the past several years lead author Jianzhu Chen the Ivan R. Cottrell Professor of Immunology a member of MIT’s Koch Institute for Integrative Cancer Research and colleagues have developed strains of mice that have the human cells necessary for a comprehensive immune response. To generate these cells the researchers deliver human hematopoietic stem cells along with cytokines