To perform the successful dendritic cell-based cancer immunotherapy one of the main issues to be solved is the source of antigen for DC pulsing. Limitations occur by using auto-tumor lysate due to the difficulties obtaining enough tumor tissue(s) quantitatively as well as qualitatively. In this study the possibility of allogeneic tumor cell lysate as a DC pulsing antigen has been tested in mouse melanoma pulmonary metastasis model.

B16F10 melanoma cells (1×10⁵/mouse) were inoculated intravenously into the C57BL/6 mouse. Therapeutic DCs were cultured from the bone marrow myeloid lineage cells with GM-CSF and IL-4 (1,000 U/ml each) for 7 days and pulsed with lysate of either autologous B16F10 (B-DC), allogeneic K1735 (C3H/He origin; K-DC) or CloneM3 (DBA2 origin; C-DC) melanoma cells for 18 hrs. Pulsed-DCs (1×10⁶/mouse)_[CGP1] were injected i.p. twice with one week interval starting from the day 1 after tumor cell inoculation.

Without observable toxicity, allogeneic tumor cell lysate pulsed-DC induced the significantly better anti-tumor response (tumor scale: 2.7±0.3, 0.7±0.3 and 0.3±0.2 for saline, B-DC and C-DC treated group, respectively). Along with increased tumor specific lymphocyte proliferations, induction of IFN-γ secretion against both auto- and allo-tumor cell lysates was observed from the DC treated mice. (w/B16F10-lysate: 44.97±10.31, 1787.94±131.18, 1257.15±48.27, w/CloneM3 lysate: 0, 1591.13±1.83, 1460.47±86.05 pg/ml for saline, B-DC and C-DC treated group, respectively) Natural killer cell activity was also increased in the mice treated with tumor cell lysate pulsed-DC (8.9±_[CGP2]0.1, 11.6±0.8 and 12.6±0.7% specific NK activity for saline, B-DC and C-DC treated group, respectively).

Conclusively, promising data were obtained that allogeneic-tumor cell lysate can be used as a tumor antigen for DC-based cancer immunotherapy.