NIH funds are requested to purchase a BD Influx cell sorter that will be placed in the PI's 870 ft2 research laboratory at Massachusetts General Hospital (MGH) in Boston. The Influx is a 6- laser instrument that is a vastly improved, refined and a far more powerful cell sorter than that it will replace, the FACS Vantage. The Vantage was initially designed in the 1990s and purchased by the PI with NCRR funds in 2000;two of the four ion-gas lasers on this instrument's optical bench are over 25 years old. Due to its chronologic age, the Vantage is increasingly difficult to maintain. Far more critically, from an engineering and technological perspective it no longer offers the necessary fluorescence sensitivity, cellular throughput and high capacity 6-way sorting ability that our user base requires. Also, a rapidly increasing translational research emphasis has accentuated the need for safe, bio-contained sorting capabilities of human cells beyond the capacity of our current sorting platform. Thus, the requested Influx will be configured additionally with a Baker class II Type A2 certified HEPA filtered biosafety hood that will provide far greater protection to the operator and local environment. The requested Influx will be placed in the PI's well established Flow Cytometry Core which has been in successful operation for almost 30 years. A wide variety of studies related to cell biology, immunology, genetics, molecular biology, infectious disease, oncology and stem cell research will all benefit from the placement of this instrumentation in the PI's facility. The PI has an established track record in utilizing polychromatic cytometry for both research and clinical work and documents that the requested instrument will provide an essential resource to the needs of the research user base at MGH. This instrument will initially serve a multidisciplinary group of 28 primary investigators from 9 departments and numerous MGH Units, representing 78 NIH funded grants totaling over 44.8 million dollars. The Influx will further benefit the entire research community at MGH, who presently lack a modern cell-sorter for their NIH funded work. The entire hospital of approximately 1000 PI's has a NIH budget of about $325 million dollars. The PI has been part of the MGH research community since 1982, and his laboratory has been the only one easily available to all investigators at MGH. The laboratory has a highly skilled operator, who along with the PI collectively represents almost 60 years of well-documented experience in flow cytometry. The laboratory has the financial support of both the Department of Pathology and MGH administration and approval of the University Biosafety office for the projects outlined in this submission.