CCL4 and COVID-19: Contrastingly, stimulation with S-protein peptide pool and crosstalk with T cells invariably induced high levels of monocytic cytokines including IFN-γ–induced protein 10 [IP-10], monocyte chemoattractant protein-1 [MCP-1], IL-8, macrophage inflammatory protein [MIP-1a], and MIP-1b, providing another aspect of the role of monocytes as a main source of cytokines in the context of COVID-19.