Fusion induced reversal of dendritic cell maturation: An altered expression of inflammatory chemokine and chemokine receptors in dendritomas

Dendritic cell-mediated cancer immunotherapy employs several ways to engage tumor antigens. We have demonstrated in both pre-clinical animal studies and early clinical trials that dendritomas, highly purified hybrids between dendritic cells (DC) and tumor cells, are superior activators of anti-tumor immunity. It has been argued, however, that DC vaccines may be dysfunctional in lymph node migration. In the present study we examined inflammatory chemokine and chemokine receptor expression as well as other maturation induced genes in dendritomas produced from either immature or mature DCs in order to shed light on their capacity to migrate from injection sites to draining lymph nodes and elicit an appropriate immune response. RNA microarray analysis was used to identify gene expression profiles for inflammatory chemokines and receptors and other maturation induced genes within dendritomas, lysate-pulsed dendritic cells, immature DCs and mature DCs. Gene regulation was confirmed with relative quantification, real-time RT-PCR in a separate experiment. We found that fusion of immature DCs to tumor cells initiates maturation with respect to inflammatory chemokines, chemokine receptors and other maturation induced genes in a similar pattern as LPS matured DCs. Interestingly, we saw a reversed gene profile when mature DCs were fused to tumor cells. LPS matured DCs displayed the chemokine repertoire expected with DC maturation; however, once fused to tumor cells, these chemokines and other maturation induced genes reverted to levels comparable to immature DCs. It appears that mature DCs used for dendritoma production result in a de-mature genotype. Our results indicate that dendritomas from immature DC/tumor cell fusions may be more effective in migration from injection site to draining lymph nodes and, therefore, would be more effective in stimulating anti-tumor immunity.