Leukemia Cell-Derived Exosomes Targeted Dendritic Cells Can Induce More Strong Anti-Leukemia Response Than Exosomes Alone

Abstract 4278

Exosomes are the newest family number of ‘bioactive vesicles’ that play important roles in antigen presentation. Recent clinical trials about exosomes have shown minor clinical benefit. However, exosomes derived from leukemia cell lines were less studied, In this study, we investigated the biological properties and anti-leukemia immunity of leukemia cell-derived exosomes (LEX). The results showed that like other tumor cells, similarly, leukemia cells can release exosomes too. Transmission electron microscopy showed that exosomes derived from NB4 cell, a promyloblastic leukemia cell line and K562 cell, a chronic myeloid leukemia cell line were membrane vesicles with diameter about 50–100μ m, and loading their specific moleculars such as RAR-α and ABL and adherent moleculars such as ICAM-1. Similarly, our data also demonstrated the presence of Hsp70 in these two leukemia cell-derived exosomes. The data from two-dimensional electrophoresis of K562 cell-derived exosomes showed that most of molecules expressing on leukemia cells were detected on their exosomes, indicating that LEX load most of proteins expressed on their original leukemia cells. Out data also demonstrated that LEX can induce anti-leukemia CTL response and LEX-targeted DC can induce more efficient anti-leukemia immunity compared with LEX alone. In conclusion, exosome-based therapies could be considered as a promising strategy to prolong disease-free survival in patients with leukemia after consolidation or hematopoietic stem cell transplantation.