The short and long-term objective of this proposal is to upgrade the School of Dental Medicine (SDM) Flow Cytometry Core Facility so that it may continue to operate with state-of-the-art equipment. The facility is currently equipped with a 20 year-old instrument that can no longer be maintained on service contracts as it has been designated as obsolete by the manufacturer. Funds are requested to purchase a high-end flow cytometer;specifically, we plan to purchase a Becton Dickinson LSR II cell analyzer. The BD LSR II is an air-cooled, four laser (488nm, 633nm, 405nm and 355 nm) benchtop flow cytometer with the capability of acquiring 10 fluorescence parameters as configured. This configuration will provide the flexibility to meet the diverse needs of our user group. Moreover, it will support our investigators as they expand their studies to larger numbers of fluorochromes and thereby obtain significantly more information per cell. Investigators will be able to monitor: a wide range of both surface and intracellular markers, assess changes in cellular concentrations of ions such as calcium, cell cycle distribution, signaling pathways as well as study protein-protein and protein-lipid interactions. Core research facilities are vital to the success of research enterprises such as that at the SDM by providing investigators with access to advanced technologies in their research activities, which for financial reasons, would otherwise not be affordable to the individual scientist or laboratory. The SDM Flow Cytometry Facility supports the diverse needs of over 11 scientists whose research efforts are focused on advancing oral health. Supported projects are focused, in particular, on studies on the response of oral and craniofacial tissue to physiologic and pathologic stimuli with emphasis in three areas: inflammation and immunity, infectious disease, and the biology of soft and hard connective tissue. Public Health Relevance: The SDM Flow Cytometry Facility and the requested funds for acquisition of a state-of-the-art flow cytometer are vital to ongoing studies that elucidate pathogenic mechanisms in periodontal disease, herpetic infection, oral cancer and disorders associated with the metabolism of oral tissues, among others. Of particular relevance, this facility provides the necessary support for studies that are currently funded by the NIH as well as provide for an advantage for our investigators as they compete for future federal research support to advance our knowledge of the pathogenesis of oral disease.