title: Tumor exosomes expressing Fas ligand mediate CD8+ T-cell apoptosis.
abstract: Tumor-derived immune suppression is considered to be a major mechanism of tumor evasion from the immune system destruction, however, little is known regarding the induction of T-cell functional suppression by tumor-derived exosomes. Herein, we investigate tumor-derived exosomes involved in normal immunological communications as means of inhibiting an antitumor T-cell response. Exosomes derived from LNCaP, a human prostate cancer cell line, were visualized by FACS and identified based on size (80-200 nm) in comparison to marker beads. Exosomes from tumor cell line inhibited T-cell proliferation. Dose-dependent apoptosis of T cells was induced by co-culture with tumor exosomes. Addition of anti-FasL antibody blocked the apoptosis induction by tumor exosomes. This study suggests that induction of T-cell apoptosis by tumor-derived exosomes appears to be a novel mechanism of tumor immune evasion.
authors.affiliation: London Health Science Centers, London, Ontario, Canada.
authors.forename: Ashraf J
authors.initials: AJ
authors.lastname: Abusamra
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Zhong
authors.forename: Xiufen
authors.initials: X
authors.lastname: Zheng
authors.forename: Mu
authors.initials: M
authors.lastname: Li
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Ichim
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Chin
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Min
mesh_terms: D000951:Antigens, Neoplasm / Q000276:immunology / Q000502:physiology; D017209:Apoptosis; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D018920:Coculture Techniques; D011992:Endosomes / Q000276:immunology* / Q000473:pathology; D053222:Fas Ligand Protein; D006801:Humans; D008213:Lymphocyte Activation; D008297:Male; D008562:Membrane Glycoproteins / Q000502:physiology*; D011471:Prostatic Neoplasms / Q000276:immunology / Q000473:pathology*; D048069:Tumor Necrosis Factors / Q000502:physiology*
chemical_list: D000951:Antigens, Neoplasm; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D048069:Tumor Necrosis Factors