Cyclophosphamide Potentiates the Antitumor Effect of Immunization with Injection of Immature Dendritic Cells into Irradiated Tumor

Growth of a tumor on the left flank was suppressed by direct injection of immature DCs (iDCs) into the irradiated tumor on the right thigh (IR/DC). This antitumor immune effect of IR/DC was enhanced by pretreatment with CTX (CTX+IR/DC) and this effect was related with increased number of tumor-specific IFN-gamma secreting T cells and decreased ratio of CD4(+)CD25(+)/CD4(+) T cells. The treatment with CTX+IR/DC increased or decreased the levels of IL-2 or IL-10, respectively. These results demonstrated that antitumor effect of IR/DC could be augmented by pre-treatment with low-dose CTX, suggesting a new antitumor therapeutic modality of chemoradioimmunotherapy.