Dendritic cells as adjuvants in antitumor immune therapy

While there has been considerable progress in the development of techniques to identify tumor-associated antigens, the traditional methods for delivering these antigens in the context of a tumor vaccine are, in many cases, crude and inadequate. Most adjuvants that are in principle available for such a vaccine have been discovered empirically and their mechanism of immune-stimulatory action is poorly understood. In addition, preclinical studies suggest that most of the conventional adjuvants often fail to elicit activation of both the humoral and the cellular arm of the immune system. Among other reasons, these findings have led to the application of dendritic cells (DCs) as adjuvants. In such experiments DCs were pulsed in vitro with tumor antigens which, upon in vivo application, caused tumor rejection in experimental mouse tumor systems, and such preparations indeed increased antitumor immunity in cancer patients. Recent advances in the understanding of the function of DCs and their first clinical applications in antitumor immune therapy are described.