Mesoporous silicon microparticles enhance MHC class I cross-antigen presentation by human dendritic cells

Abstract

The mesoporous silicon microparticles (MSMPs) are excellent vehicles for releasing molecules inside the cell. The aim of this work was to use MSMPs to deliver viral specific MHC class I restricted epitopes into human antigen presenting cells (monocyte derived dendritic cells, MDDCs) to facilitate their capture, processing, and presentation to CD8+ (cytotoxic) T lymphocytes. We show for the first time that MSMPs vehiculation of antigenic peptides enhances their MHC class I presentation by human MDDCs to CD8 T lymphocytes.

Figure 1

(a) Particle size distribution of MSMPs materials (nanosizer measurement) after being milled and sieved. (b) FTIR spectra of the porous silicon layers on a wafer after thermal oxidation process.

Figure 2

The scanning electron microscopy photos of the as-prepared porous silicon material: (a) in-plan view of the treated silicon wafer (×50.000), (b) transversal view of the porous material (×5.000), (c) particle surface after grinding (×50.000).

Figure 3

The microparticles are internalized into dendritic cells (DC). (a) Photographs show control cells (MDDCs) or with internalized unloaded (MDDCs-MSMPs) or peptide loaded (MDDCs-MSMPs-CEFpp) microparticles. After 24 h of incubation the cells are aggregated, and the particles are inside vacuoles ((b)-(c) and insert). Trypan blue dye was used to determine the percentage of live MDDCs relative to a nontreatment control following 24 h incubation with MSMPs (d). *P < 0.05.

Figure 4

Dendritic cells maturation by MSMPs. (a) Representative histograms of dendritic cells maturation determined by quantifying the presence of the following activation markers: HLA-class I, CD80, CD86, and HLA-class II (DR) on their cell surface by flow cytometry. Isotype: irrelevant antibody; (−): MDDCs alone; CEFpp: MDDCs exposed to antigenic peptide (CEFpp) alone; MSMPs−: MDDCs with microparticles without CEFpp; MSMPs+: MDDCs with microparticles loaded with CEFpp; LPS: lipopolysaccharide. (b) Relative mean fluorescence intensity. Mean ± SD (n = 4). *P < 0.05; **P < 0.03; ***P < 0.01.

Figure 5

Porous silicon microparticles loaded with antigens trigger the immune response. ELISPOT assays: the incubation of peripheral lymphocytes (PBMCs) from healthy donors with allogenic dendritic cells (MDDC) differentiated and matured in the presence of microparticles loaded with antigenic peptides (MSMP+) results in the activation of specific CD8 lymphocytes, showed as a synthesis of IFN-γ. PHA: phytohemagglutinin (1 μg); CEFpp: CEF peptide pool; MSMP(−): unloaded microparticles. *P < 0.05; ***P < 0.01.