TNF and hemophagocytic syndrome: In severe COVID-19, a specific cytokine profile resembling the pattern of a secondary hemophagocytic lymphohistiocytosis (HLH) has been shown, due to significant increases of IL-2, IL-7, granulocyte colony stimulating factor (GCSF), interferon-γ inducible protein 10 (IP-10), monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein 1-α, and tumor necrosis factor (TNF) (6).