Standardized generation of fully mature p70 IL-12 secreting monocyte-derived dendritic cells for clinical use

Dendritic cells (DC) have been shown to be efficient antigen-presenting cel ls (APC) and, as such, could be considered ideal candidates for cancer immu notherapy. Immature DC (iDC) efficiently capture surrounding antigens, howe ver, only mature DC (mDC) prime naive T lymphocytes. Clinical trials using DC-based tumor vaccines have achieved encouraging, but limited, success, po ssibly due to the use of immature or incompletely mature DC. Thus, it was a pparent that a method capable of generating large numbers of fully function al iDC, their pulsing with desired form of tumor antigens and the subsequen t complete and reproducible maturation of iDC is needed. Therefore, we comp ared two different methods of producing large numbers of iDC. Both protocol s yielded comparable numbers of cells with an iDC phenotype with phagocytic function. We next determined which of the clinically applicable activators could induce the complete and reproducible maturation of DC, in order to d efine the most suitable combination for future clinical trials. Only a comb ination of TNF alpha + Poly (I:C), or a previously described cytokine cockt ail of TNF alpha+ IL-1 beta + IL-6 + prostaglandin E-2, induced the complet e activation of the whole DC population, as assessed by the cell surface ex pression of CD83 and costimulatory molecules. The matured DC were functiona lly superior to iDC in their ability to stimulate the proliferation of allo geneic lymphocytes and autologous keyhole limpet hemocyanin (KLH)specific T lymphocytes. Furthermore, only the combination of TNF alpha + Poly (I:C) a ctivated DC to produce large amounts of biologically active p70 IL-12. Thus DC maturation by TNF1 alpha + Poly (I:C) could efficiently bias T cell res ponse towards Th1 response. Implementation of our results into clinical pro tocols used for DC generation could be beneficial for future immunotherapy trials.