PROJECT SUMMARY Sanford Burnham Prebys Medical Discovery Institute (SBP) has ~40 labs studying the molecular and cellular underpinnings of diverse biological processes including cancer; developmental biology; immuno-oncology; infection, inflammation; aging and related diseases. Many recent advances in health care depend upon new insights into tissue heterogeneity at the single cell level. Flow cytometry is the gold standard for high throughput single cell analysis, however conventional flow is limited by the number of analytes that can be run in unison. Spectral flow cytometers recently achieved the parameter depth required for deep immune profiling with publications showing 40+ color rivaling time-of-flight mass cytometry (CyTOF) parameter depth with ~50-fold higher throughput. SBP requests support for a Cytek Aurora Spectral Flow Cytometer with 5 lasers (UV/V/B/YG/R), 64 fluorescence and 3 scattering channels, and Automatic Micro-sampling Station (AMS) to enable high- parameter single-cell proteomic analysis for deep profiling of cell heterogeneity in tissues. We also request support for a BioBUBBLE Class I Negative Biocontainment Enclosure for Cytek Aurora to protect researchers running potentially infectious material. The Aurora more than doubles the number of fluorescent parameters that can be measured at SBP and leverages existing FACS protocols and expertise. It is a bridging technology between high-throughput low-plex conventional flow cytometers in SBP’s Core and high-plex low- throughput genomics-based single-cell Seq technologies. This application is supported by a coalition of 12 Major Users from SBP and nearby University of California San Diego (UCSD) and San Diego Biomedical Research Institute (SDBRI) demonstrating the broad impact for the region. NIH-funded researchers, together accounting for 75% of the Aurora’s available use time (AUT), need the Aurora to advance their understanding of T cell exhaustion, anti-tumor immunity, aging, multi-system inflammatory disease in children (MIS-C), gut mucosal immunity, melanoma, pancreatic cancer, breast cancer, pediatric medulloblastoma, graft versus host disease, and the immune evasion tactics of Coronavirus. The Aurora will provide unprecedented insight into tissue signatures that correlate with health and disease leading to new mechanistic inquiries and discoveries.