[Cytotoxicity of dendritic cells pulsed by CpG ODN on ovarian carcinoma cells: in vitro experiment with ovarian carcinoma cells].

OBJECTIVE

To investigate the effect of dendritic cells (DCs) pulsed by oligonucleotide containing "un-methylated cytimidine-phosphodiester bond-guanylic acid" motif (CpG ODN) on ovarian carcinoma cells.

METHODS

Dendritic cells were isolated form the peripheral monocytes and co-incubated with synthesized CpG2006, CAI125, important epithelial ovarian cancer-associated antigen, or CpG ODN + CA125 for 72 h. Flow cytometry (FC) was used to detect the expression of CD(1alpha), CD(63), CD(86), and human leucocyte antigen-DR (HLA-DR) on the cell surface. ELISA was used to detect the IL-12 level in the supernatant. T cells were obtained from the DCs. The suspensions of different groups of pulsed DCs were co-incubated with T cells. Mixed lymphocyte reaction (MLR) was used to detect the proliferating activity of the T cells. Ovarian carcinoma cells of the line OVCAR-3 were added into the culture fluid of T cells with different effector-target ratios, and then unpulsed DCs, CpG ODN-pulsed DCs, CpG ODN + CA125-pulsed DCs, and CA125-pulsed DCs were added respectively. MTT colorimetry was performed to measure the A values of different wells so as to calculate the killing rate.

RESULTS

(1) The expression levels of CD(63), CD(86), and HLA-DR on the membranes of the CpG ODN-pulsed DCs and CpG ODN + C125-pulsed DCs were significantly higher than those of the un-pulsed DCs (all P < 0.01), however, there were no significant differences in the expression of CD(1alpha) among different groups (all P > 0.05). (2) The IL-12 levels in the supernatants of the CpG ODN-pulsed DCs and CpG ODN + C125-pulsed DCs were significantly higher than those of the unpulsed and CA125-pulsed groups (all P < 0.01). (3) MLR showed that the T cell proliferation rates of the T cells sensitized by the CpG ODN-pulsed DCs and CpG ODN + C125-pulsed DCs were both higher than those of the T cells stimulated by the unpulsed and CA125-pulsed groups when the effector: target ratio was 10:1 (all P < 0.01). (4) The killing rates on OVCAR-3 cells of the CTLs sensitized by CpG ODN + CA125-pulsed DCs at the same effector: target ratios were all higher than those of the CTLs sensitized by the CpG ODN-pulsed DCs, CA125-pulsed DCs, and unpulsed DCs (all P < 0.01), the killing activity of the cytotoxic T lymphocytes (CTLs) sensitized by CpG ODN+CA125-pulsed DCs on the OVCAR-3 cells was shown even when the effector: target ratio was as low as 10:1, and then increased along with the increase of the effector: target ratio to the height of 64.9%.

CONCLUSION

Capable of inducing immune cytotoxicity on ovarian carcinoma, DCs sensitized by CpG ODN + CA125 may have a great implication on clinical application.