Objective       To investigate the change and function of toll-like receptor 4 (TLR4)/Mye-loid differentiation factor 88 (MyD88) signal transduction pathway in fusion vaccine by peripheral blood dendritic cells and renal cell carcinoma 786-0 cells.      Methods      Peripheral blood sample of healthy volunteers was used to induce immature dendritic cells (imDCs)

which were further induced to fuse with renal cell carcinoma (RCC) 786-0 cells with aid of polyethylene glycol (PEG). Transmission electron microscopy (TEM) was employed to observe the changes of imDCs before and after fusion. Semi-quantitative RT-PCR was used to detect the mRNA changes of TLR4 and MyD88 in pure imDCs

RCC 786-0 cells

and imDC-RCC 786-0 fusion vaccine in 6

12

24

and 48 h after fusion. The transposition of nuclear fac-torkappa B (NF-κB) in imDCs before and after fusion was detected by laser scanning confocal microscopy (LSCM). The changes of CD86 and HLA-DR in imDCs before and after fusion were detected by flow cytometry. The abilities of the fusion vaccine to stimulate T lymphocytes proliferation and CTL cells-mediated antitumor response were measured by MTT assay.      Results       Transmission electron microscopy showed imDCs were transformed to mDCs after fusion. The mRNA of TLR4 and MyD88 was not expressed in RCC-786-0 cells

mildly expressed in imDCs

but was significantly strongly expressed in fusion vaccine in 6 h after fusion (P0.05)

then their mRNA expression was decreased gradually till undetectable in 48 h after fusion. LSCM displayed that NF-κB existed in the cytoplasm of pure imDC

and then translocated in the nucleus of fusion vaccine. The expressions of CD86 and HLA-DR in fusion vaccine were significantly upregulated compared with the pure imDC control group (P0.05). The functions of dendritic cell-tumor fusion vaccine to stimulate the proliferation of T lymphocytes were stronger than that of imDCs

RCC 786-0 cells (P0.05)

and CTLs stimulated by the fusion vaccine showed distinct activity in vitro to kill autologous tumor cells.      Conclusion       TLR4/MyD88-NF-κB signal transduction pathway exhibits an very significance role in fusion vaccine to promote imDCs to shift mDCs

and the signal pathway prompts dendritic cells function changes.