Aim: To study the effect of microenvironment simulated by esophageal carcinoma homogenate supernatant on the differentiation and development of human dendritic cells (DCs) and to investigate the mechanisms of tumor immune escape for the clinical application of DC vaccines.
Methods: Fresh esophageal carcinoma and peri-cancer tissues were collected to prepare homogenate supernatant and the content of VEGF-A was detected by ELISA. The peripheral blood monouclear cells were isolated by density gradient centrifugation and cultured with RPMI1640 medium including rhGM-CSF and rhIL-4 to induce to DCs. Then the esophageal carcinoma homogenate supernatant, peri-carcinoma homogenate supernatant and VEGF-A were added on the second day and half of the medium was changed every other day. Antigen of esophageal carcinoma cell line EC9706 was added on day 4 and lipopolysaccharide (LPS) was added on day 6. DCs were collected on day 8 for further study. Checked the morphology of DCs by microscope, the immunophenotype by flow cytometry, the gene of CD1a by RT-PCR and the proliferation and killing rate of T cell by CCK-8.
Results: The content of VEGF-A in the homogenate supernatant of esophageal carcinoma was significantly higher than that of the peri-carcinoma (0.987+/-0.319 microg/L, 0.152+/-0.105 microg/L, P<0.05). The cell morphology in esophageal carcinoma homogenate supernatant group was inhibited. Besides, compared with normal DCs, the positive expression rate of CD86 decreased from 69+/-8 to 42+/-11, CD1a decreased from 56+/-12 to 27+/-12 and CD11c decreased from 21+/-13 to 18+/-13 (P<0.01). CD1a gene almost showed no expression. The proliferation capacity of T cells decreased from 112.53+/-7.16 to 70.18+/-3.47 (P<0.01), and their killing capacity of T cells decreased from 62.42+/-0.57 to 46.81+/-1.62 (P<0.01). However, the cells had no difference among peri-carcinoma homogenate supernatant group, VEGF-A group and normal DC group.
Conclusion: The tumour microenvironment stimulated by the esophageal carcinoma homogenate supernatant obviously has inhibitory effect on the differentiation and function of DCs.VEGF-A may not be the key factor in the process.