Escalating concentrations of recombinant spike can activate human lung macrophages, triggering the production of proinflammatory cytokines that mirror the “cytokine storm” signature observed in clinical COVID-19 cases (IL-2, IL-4, IL-6, IL-1β, IL-8, IFN-γ, TNF-α, and CXCL10) [40,41]. Here, CXCL10 is linked to COVID-19.