Progress in research on biological characteristics of exosomes and therir roles in tumor immunotherapy

Exosomes are membranous vesicles secreted by living cells into the extracellular environment, at diameters of 50 ∼ 100 nm. There are lots of proteins and lipids on the surface of exosomes, which are closely related to their structure and function. Exosomes could be released by many kinds of cells. Exosomes have various important functions, especially in tumor immunotherapy. Exosomes from DCs and tumor cells showed good curative effect on tumors in recent studies, which have become a hotspot in the research of oncology. This review summarizes the biological origin, biological characteristics and physiological functions of exosomes as well as their action mechanism in diagnosis and immunotherapy of tumors.