Figure 5

Inability to internalize PEG-HCCs leaves key macrophage functions unaltered.

(a) Percentage of migratory ovalbumin-specific T cells through a 5 μm transwell filter when the bottom chamber contained supernatant from LPS-stimulated macrophage cultures, used as a readout for adequate macrophage production of T cell chemoattractants. Green bars: Macrophages incubated with PEG-HCCs during LPS-stimulation and T cells left untreated. Blue bars: Macrophages left untreated during LPS-stimulation and T cells incubated with PEG-HCCs and washed prior to the transwell assay. Bottom chambers containing medium alone, medium supplemented with 5% FBS, or supernatant from unstimulated macrophages are shown as controls (n = 3 replicates). (b) Left, representative images of macrophage phagocytosis of Alexa Fluor 488-conjugated bioparticles (green) in the absence of nanoparticles (control) or in the presence of PEG-HCCs or Fe₃O₄ nanoparticles. Macrophage nuclei were stained with DAPI (blue). Right, quantification of the phagocytosis assay (n = 100 cells/rat; N = 3 rats spleens, two-tailed Student’s t test). Scale bars, 5 μm. (c) Proliferation of ovalbumin-specific T cells stimulated in the presence of antigen-loaded macrophages, used to gauge adequate macrophage antigen processing and presentation. Green bars: Macrophages incubated with PEG-HCCs during antigen loading. Blue bars: PEG-HCCs added at same time as T cells. Macrophages not loaded with antigen (unstimulated) were used as a control (n = 3 experiments). (d) Aspergillus niger fungus growth prevention by rat splenic macrophages treated with the indicated doses of PEG-HCCs (n = 3 experiments). Mean ± s.e.m. *P < 0.05, **P < 0.01, ***P < 0.001.