The National Institute of Allergy and Infectious Diseases (NIAID), Research Technologies Branch (RTB), Flow Cytometry Unit (FCU) is seeking to acquire one (1) FACSymphony S6 SE Cell Sorter System (or equal) with the associated twelve-month (12) maintenance agreement for parts and labor, feasible acquisition alternatives, the impact of prior acquisitions on those alternatives, and any related in-house effort. The Flow Cytometry Unit provides DIR with application-specific flow cytometric technologies, including instrumentation and multi-color analysis. In addition, the FCS provides training, consultation, method development, and analysis for experiments involving flow cytometry. This mission is accomplished through the efforts of staff with extensive flow cytometry experience and with the use of cell sorters and analyzers. Major goals are to provide access to state-of-the-art technologies, to help design and run experiments, to facilitate data interpretation, and to provide results that are of consistent high quality.