PROJECT SUMMARY This Leica Stellaris 8 DIVE system is a multiphoton microscope for intravital imaging with video rate data acquisition, deep tissue penetration, high sensitivity, and uses cutting edge spectral detection technology. This system will replace a 12-year-old multiphoton microscope system that is no longer supported by the vendor and currently off-line. More than 20 research faculty in the Center for Immunology at the University of Minnesota depend on this instrument, and their research has been put on hold until the instrument can be repaired (which seem increasingly less likely) or replaced. Among those faculty are the 6 NIH funded investigators that constitute the major and minor users of this proposal. Multiphoton microscopy is used to collect optical data to determine cellular movement and cellular interactions using fluorescent vital dyes and genetically encoded fluorescent proteins. Using this technology, immunologists are investigating the cellular and molecular mechanisms controlling cell motility, cellular interactions, and signals within intact tissues of living animals. The Leica Stellaris 8 DIVE system will allow researchers to perform intravital multiphoton imaging deep in tissue specimens to examine 4 different fluorescent signals or cell types simultaneously. Research conducted by the investigators involved in this grant span multiple disciplines relating to public health including autoimmunity, transplantation, cancer, immune activation, host/pathogen responses, vaccine design and infectious diseases. The equipment obtained using these funds will allow our group to continue to perform novel and cutting-edge biological imaging using multiphoton microscopy to pursue fundamental knowledge regarding human health in these research areas. This technology will significantly enhance our ability to achieve research aims to diagnose, treat, and protect individuals afflicted with a wide variety of conditions, and will greatly aid in preventing and curing human diseases. Therefore, purchase of a new turn-key commercial instrument will ensure our sustainability and access to this critical technology to achieve the aims of the NIH funded investigators described in this proposal and provide cutting-edge technology for immunology researchers at the University of Minnesota in the Center for Immunology.