None of the polymers showed toxicity at the tested concentrations (Figure ). Remarkably, all the polyglycerol sulfates significantly reduced the release of IL-13 from CD4 + lymphocytes (Figure ). Here, dPGS10, the smallest and highly sulfated polyglycerol, showed the most potent effect, leading to a significant IL-13 reduction at 1 ng/mL (p < 0.0.5). Other polymers required higher concentrations to significantly reduce IL-13 release: 10 ng/mL for lPGS10, 100 ng/mL for dPGS50, and 1000 ng/mL for dPGS100. The potent anti-inflammatory effect we observed is in accordance with the strong binding of polyglycerol sulfates to TSLP via electrostatic interactions as shown in Figure . Interestingly, HS also led to a significant IL-13 reduction at 1 ng/mL.