We request funds to purchase from Becton Dickinson (BD) a new 5-laser, 30-color FACSymphony A5 analytic flow cytometer. The new A5 instrument will replace our 15-year-old, 5-laser, 18-color BD LSR II instrument that BD will no longer support with a service contract after September 2022. The new A5 instrument will support the research of 14 major users and 32 minor users holding 51 NIH grants, as well as projects supported by the Department of Defense, private industry, and foundations. We will install and configure the new Symphony A5 instrument to closely match our existing Symphony A5, which is the most-used instrument in the Flow Cytometry and Single Cell services (FCSC) Core. By configuring the new A5 instrument to match the existing one, our Core personnel and users will be already trained to operate the new instrument and its onboard software. Moreover, users who already have multi-parameter antibody panels designed to work on the existing Symphony A5 can use these antibody panels on the new A5 without modification, thereby easing scheduling constraints. Based on the prior use of the existing LSR II and Symphony A5 instruments, we project that the new A5 instrument will be used 34 hours/week (85% of the Accessible User Time, AUT). The new A5 instrument will be administered by the FCSC Core and will be incorporated into the Core's existing financial plan. The FCSC Core is part of the UAB-wide Institutional Research Core Program (IRCP) and as such, the FSCS Core receives significant institutional support from the IRCP. Three highly experienced flow cytometry specialists, each trained to operate the Symphony A5, are available to train new users in instrument operation and to assist them with the development of multi-parameter antibody panels. Finally, the FCSC Core is located in the Shelby Biomedical Research Building, a building that houses the research laboratories of most of our major users and is within a short walking distance of our other users on campus. Thus, the requested new Symphony A5 instrument will fill a critical void in the FCSC Core and will allow us to continue to provide state-of-the-art instruments and services to our users.