UCB Tregs decrease systemic inflammation in CAR T cell recipients. (A). Multiple inflammatory cytokines decreased in UCB Treg recipients: (i) Eotaxin; (ii) GM-CSF; (iii) IFN-α; (iv) IFN-γ; (v) IL-13; (vi) MCP-1; (vii) MCP-3; and (viii) soluble CD40 ligand (sCD40L). (B). CAR T vs. CAR T + UCB Tregs shows the anti-inflammatory impact of UCB Tregs. Specifically, when compared to CART recipients, the addition of UCB Treg cells clearly decreased the burden of several inflammatory cytokines. Error bars represent SEM (n = 7); statistical differences compared with the control arm were quantified by one-way ANOVA using GraphPad Prism software: * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001. PB, peripheral blood; FI, Fluorescent Intensity. The corresponding cytokine concentration of the FI can be calculated with the standard curve. We simply use FI as the unified equivalent of different cytokines.