This application note demonstrates how the ID7000™ Spectral Cell Analyzer enables high-dimensional immune profiling using a 45-color spectral flow cytometry panel to study age-associated changes in the human immune system. The panel was designed to characterize diverse leukocyte populations, including T cells, B cells, NK cells, dendritic cells, monocytes, and hematopoietic stem cells, while incorporating markers for lineage, function, and senescence. This optimized panel delivers high-resolution analysis with excellent spectral separation and minimal spreading error, supporting deeper insight into immune aging and complex immune cell remodeling within a single experiment.