kinetic model incorporated in FIRM. The model accounts for Treg presence in the lymphoid T (where they differentiate from naïve T-cells), the blood (where they migrate and are subject to removal or recruitment to the target organ) and the target organ (where they proliferate). The kinetics of TGF-β are similarly accounted for. Treg, regulatory T-cells; TGF-β, tumor growth factor beta; other abbreviations as in Figure 1A and Figure 1B. See text for details.