Fig. 2 Notch and IL-6 cooperate to activate the immune system and perpetuate the cytokine storm. In macrophages, Dll4/Notch signalling promotes the production of infammatory cytokines, IL-6 among those. IL-6, in turn, increases the expression of the Notch ligands (Dll1,4), thus amplifying the Notch signalling and establishing a feedback loop that promotes the further production of IL-6. In T cells, Notch signalling triggered by Dll1/Dll4 ligands promote infammatory Th1/Th17 cytokines; on the contrary, Jagged1 ligands dampen IL-6-induced Th17 activation. Tocilizumab is expected to block cytokine storm and prevent tissue damage. Notch inhibition by blocking Dll1,4 ligands may help to interrupt the positive feedback loop that fuels the cytokine storm. M Macrophages, T T cells