Fig. 4.

PD-1-targeting nanoparticles bind to activated human T cells. a PD-1 expression on human CD3⁺ T cells following activation with anti-CD3/CD28 complex, n = 4 independent donors, mean ± s.e.m. b Dose-dependent binding of PD-1-targeting nanoparticles to 250,000 activated human T cells. c Quantification of T cells that were bound by DiD-loaded, PD-1-targeting nanoparticles; graph shows results of two donors and is representative for at least two independent experiments. d Dose-dependent binding of PD-1-targeting nanoparticles to activated and non-activated peripheral blood mononuclear cells (PBMCs), n = 4, mean ± s.e.m. e Pre-incubation of activated human T cells with free pembrolizumab (pre pembro) for 30 min blocks binding of PD-1-targeting nanoparticles (10 µg per 200,000 T cells; n = 3, mean ± s.d.) (*p < 0.05; **p < 0.01, Two-tailed student’s t-test)