CXCL9 and COVID-19–associated multisystem inflammatory syndrome in children: In the context of SARS-CoV-2-related inflammation, rapid activation of Th1 cells and monocytes drives increased production of IL-6, tumor necrosis factor α (TNF-α), interferon gamma (IFN-γ), as well as IL-1β, IL-8, IL-10, IL-15, IL-17, and IL-18 [15, 46, 50].They identified that CXCL9, a chemokine induced by IFN-γ, showed a disproportionately greater expression in response to IFN-γ in MIS-C patients compared with non-MIS-C cohorts, suggesting a cytokine amplification cascade at the center of MIS-C pathogenesis [46].