Fig. 1

Potential utility of cytometric profiling to understand the sepsis immune response. Peripheral blood leukocytes from patients with sepsis can be assayed by either flow cytometry or mass cytometry (cytometry by time-of-flight [CyTOF]) to understand cell populations and, via their expression patterns, their degree of activation or exhaustion. Along with plasma protein analysis which could inform about cytokine elaboration, immune cell profiling might detect the source of inflammatory proteins and identify specific deleterious patterns. Cytotoxic T cell activation, which is associated with poor outcomes in sepsis and COVID-19 and contributes to tissue damage, may be due to antigen-driven processes that are necessary for pathogen control, or it may result from bystander activation. Discriminating between these patterns may be essential to best design strategies to intervene in pathologic activation yet preserve patho- gen clearance. TNF tumor necrosis factor, IL interleukin, IFN interferon, MCP monocyte chemoattrac- tant protein, PFN perforin, GzmB granzyme B, TCR T-cell receptor. Figure created with BioRender.com