Dendritic cells: potential role in cancer therapy.

Dendritic cells (DC) are extremely potent antigen presenting cells, uniquely capable of sensitizing naive T cells to protein antigens and eliciting antigen specific immune responses. Studies of human DC isolated from peripheral blood indicate that these cells can be used to stimulate and expand antigen specific CD4+ and CD8+ T cells, in vitro. On the basis of these findings we have initiated pilot clinical studies to investigate the ability of DC pulsed ex vivo with tumor associated proteins to stimulate host anti-tumor immunity when re-infused as a vaccine. In the first such study DC pulsed with tumor derived idiotype protein were infused into patients with low grade malignant B cell lymphoma who had failed conventional chemotherapy. The majority of treated patients developed T cell mediated anti-idiotype immune responses and some of the patients experienced tumor regression. These results suggest that DC based immunotherapy is a potentially useful approach to B cell lymphoma and raises the possibility that the approach may prove useful in the treatment of other tumors as well.