We have completed and published our work on biodegradable poly (D, L-lactide-co-glycolide) (PLGS) micropsheres (MS) coencapsulating ligands for endosomally expressed TLRs plus exogeneous Antigen (Ag) to deliver its cargo to endosomes of murine Dendritic cells (DCs), thus initiating TLR mediated DC maturation as well as processing of MHC class I and class II restricted epitopes.

A proteomics map of lysosomes purified from non-activated and activated mouse DCs was established.

We showed that, in the absence of adjuvants, DEX mediate potent antigen dependent-antitumor effects against preestablished tumors in mice pretreated with immunopotentiating dosing of cyclophosphamide (CTX). CTX could i) abolish the suppressive function of CD4+CD25+Foxp3+ regulatory T cells (Treg), ii) markedly enhance the magnitude of secondary but not primary CTL responsesinduced by DEX vaccines, iii) synergize with DEX in therapy but not prophylaxis tumor models.

Exosomes were used to treat a chohort of 77 gastrointestinal stromal tumor (GIST) cancer patients.

DC exosomes along with various TLR ligands or cytokines such as IL-2 or alpha IFN were used to promote Mart-1 specific T cell priming and/or NK cell triggering in HHD2 mice. We demonstrated that only TLR3 and 9 ligation is able to induce CTL priming in vivo. However, exosomes in the absence of adjuvants can induce NK cell activation.

Dendritic cell (DC) derived-exosomes (Dex) were described as nanovesicles harbouring functional MHC molecules stimulating T cell responses. Mouse studies unraveled the bioactivity of Dex onto NK cells, Dex promoting a IL-15Ra-dependent NK cell proliferation and a NKG2D-dependent activation resulting in an anti-metastatic effect. In humans, Dex bear functional IL-15R? which allow proliferation and IFNg secretion by NK cells. In contrast to immature DC, human Dex harbor NKG2D ligands on their surface leading to a direct engagement of NKG2D and NK cell activation ...

Exosomes bearing functional MHC-peptide complexes have been shown to be presented at the surface of recipient DCs as intact "antigen-presenting microdomains", without the need for internalisation and reprocessing by the DC.

The exosomes were used to immunize mice, hybridomas were generated that produce antibodies recognizing at least the human exosomes.

We have finalized analysis of the receptors on DCs responsible for capture of exosomes secreted by mature DCs. We have shown that expression of LFA-1, but not of Mac-1, integrin, on DCs is required for capture of ICAM-1-bearing exosomes.