Mechanism of Differential Ag-specific Immune Induction by Different Tumor Cell Lysate Pulsed DC

BACKGROUND: Tumor cell lysate has been considered as a preferential antigen source for the therapeutic dendritic cell pulsing. Our experiences with in vivo study with animal tumor model indicate the tumor cell lysate dependent differential effect of DC therapy. Our previous data show that MC38 lysate pulsed-DC induced stronger ag-specific immunity than CT26 lysate pulsed-DC in vitro. In this study we tried to reveal the mechanism for differential induction of ag-specific immunity of different colon cancer cell lysate pulsed-DCs. METHODS: MC38 and CT26 cell lines were prepared as lysate by freezing-thawing procedure. Tumor cell antigenicity was confirmed by detecting the surface expression of MHC I/II & B7.1/2 molecules. IL-10, IL-12 and TGF-beta in the tumor cell lysate were detected by ELISA and the presence of heat shock proteins were analysed by western blotting. RESULTS: The secretion of IL-10, a immune-inhibitory cytokine was about 470% higher in CT26 lysate than in MC38. Hsp 70 was detected only in the MC38 lysate but not in the CT26. On the other hand, Hsp 60 and 90 expression were not different in two colon cancer cell lysates. CONCLUSION: In two different colon caner cell lysate, immune inhibitory IL-10 (higher in CT26) and Hsp70 (MC38 superiority) were differentially expressed. These data indicate that higher ag- specific immunity induction by MC38 lysate pulsed-DC may due to the expression of hsp70 and lower secretion of IL-10, a immune-inhibitory cytokine than CT26 lysate. The significance of other cytokine and the surface marker expression will be discussed.

Anti-cancer Effect of Hematopoietic Stem Cell-derived Allogeneic-DC Vaccine in Melanoma Metastasis Model

BACKGROUND: Dendritic cell (DC)-based cancer immunotherapy is studied for several years. However, it is mainly derived from autologous PBMC or leukapheresis from patient, which has limitations about yield and ability of DC production according to individual status. In order to solve these problems, inquiries about allogeneic DCs are performed but there are no preclinical trial answers for effect or toxicity of allogeneic DC to use for clinical trial. In this study, we compared the anti-tumor effect of allogeneic and autologous DCs from mouse bone marrow stem cells in mouse metastatic melanoma model. METHODS: B16F10 melanoma cells (5 x 10(4)/mouse) were injected intravenously into the C57BL/6 mouse. Therapeutic DCs were differentiated from autologous (C57BL/6: CDC) or allogeneic (B6C3F1: BDC) bone marrow stem cells with GM-CSF, SCF and IL-4 for 13days and pulsed with B16F10 tumor cell lysate (Blys) for 18hrs. DC intra-peritoneal injections began on the 8th day after the tumor cell injection by twice with one week interval. RESULTS: Anti-tumor response was observed by DC treatment without any toxicity especially in allogeneic DC treated mice (tumor burden score: 2.667+/-0.184, 2.500+/-0.463, 2.000+/-0.286, 1.500+/-0.286, 1.667+/-0.297 for saline, CDC/unpulsed-DC: U-DC, CDC/Blys-DC, BDC/U-DC and BDC/Blys-DC, respectively). IFN-gamma secretion was significantly increased in allogeneic DC group stimulated with B16F10 cell lysate (2,643.3+/-5,89.7, 8,561.5+/-2,204.9. 6,901.2+/-141.1 pg/1 x 10(6) cells for saline, BDC/U-DC and BDC/Blys-DC, respectively) with increased NK cell activity. CONCLUSION: Conclusively, promising data was obtained that allogeneic DC can be used for DC-based cancer immunotherapy.