Malignant effusions and immunogenic tumour-derived exosomes.
BACKGROUND
Exosomes derived from tumours are small vesicles released in vitro by tumour cell lines in culture supernatants. To assess the role of these exosomes in vivo, we examined malignant effusions for their presence. We also investigated whether these exosomes could induce production of tumour-specific T cells when pulsed with dendritic cells.


METHODS
We isolated exosomes by ultracentrifugation on sucrose and D(2)O gradients of 11 malignant effusions. We characterised exosomes with Western blot analyses, immunoelectron microscopy, and in-vitro stimulations of autologous T lymphocytes.


RESULTS
Malignant effusions accumulate high numbers of membrane vesicles that have a mean diameter of 80 nm (SD 30). These vesicles have antigen-presenting molecules (MHC class-I heat-shock proteins), tetraspanins (CD81), and tumour antigens (Her2/Neu, Mart1, TRP, gp100). These criteria, including their morphological characteristics, indicate the similarities between these vesicles and exosomes. Exosomes from patients with melanoma deliver Mart1 tumour antigens to dendritic cells derived from monocytes (MD-DCs) for cross presentation to clones of cytotoxic T lymphocytes specific to Mart1. In seven of nine patients with cancer, lymphocytes specific to the tumour could be efficiently expanded from peripheral blood cells by pulsing autologous MD-DCs with autologous ascitis exosomes. In one patient tested, we successfully expanded a restricted T-cell repertoire, which could not be recovered carcinomatosis nodules.


CONCLUSIONS
Exosomes derived from tumours accumulate in ascites from patients with cancer. Ascitis exosomes are a natural and new source of tumour-rejection antigens, opening up new avenues for immunisation against cancers.
Andre
Fabrice
F
Departments of Clinical Biology, Immunology Unit, Institut Gustave Roussy, Villejuif, France.
Schartz
Noel E C
NE
Movassagh
Mojgan
M
Flament
Caroline
C
Pautier
Patricia
P
Morice
Philippe
P
Pomel
Christophe
C
Lhomme
Catherine
C
Escudier
Bernard
B
Le Chevalier
Thierry
T
Tursz
Thomas
T
Amigorena
Sebastian
S
Raposo
Graca
G
Angevin
Eric
E
Zitvogel
Laurence
L
D000230:Adenocarcinoma / Q000276:immunology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000276:immunology / Q000302:isolation & purification*; D002277:Carcinoma / Q000276:immunology*; D022162:Cytoplasmic Vesicles / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D005260:Female; D006801:Humans; D058965:MART-1 Antigen; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000302:isolation & purification; D016066:Pleural Effusion, Malignant / Q000166:cytology / Q000276:immunology*; D014407:Tumor Cells, Cultured
D000951:Antigens, Neoplasm; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins