OBJECTIVETo study the tumor cell killing function of T lymphocytes stimulated by dendritic cells (DC) and to analyze the differences of protein contents of exosomes in each type of cell.

METHODSThe exosomes of hepatic cell lines with high (P group) or low (F group) metastatic potentials were isolated by a process of four-step centrifugation and the collected exosomes were observed under an electron microscope (EM). The tumor cell killing experiment was performed by adding T lymphocytes activated by DC loaded with exosomes from corresponding P and F group cells and was studied using 3H-TdR experiments. The proteomic analysis was performed by surface-enhanced laser desorption/ ionization time of flight mass spectrometry (SELDI-TOF-MS ) on the exosomes of P and F group cells.

RESULTSThe density distribution and content of exosomes in the P group were not equal to those in the F group observed by EM. The CD80, CD86, MHC-I and MHC-II in the P group were 64.27+5.00, 44.89+10.11, 84.35+19.89 and 59.03+19.37, and those in the F group were 71.53+4.85, 50.01+9.50, 80.68+29.87 and 58.86+21.11, respectively (P>0.05, compared with the control group). The counts per minute value in the P group was 528.40+179.06 and 78.80+24.44 in the F group after being loaded with exosomes (P<0.01, compared with the control group). There were significant differences between the proteins in the exosomes of hepatic cancer cell lines with high or low metastatic potentials.

CONCLUSIONExosomes have potential values of application in immunotherapy and in biotherapy for recurrences and metastases of hepatic carcinomas.