Antigen loading of dendritic cells with apoptotic tumor cell-preparations is superior to that using necrotic cells or tumor lysates.

Loading of dendritic cells (DCs) with tumor cell (TC) preparations is an attractive method for vaccine preparation because the entire antigen repertoire of a tumor is processed and presented by the DCs, thus allowing the simultaneous stimulation of T-helper cells and cytotoxic T-lymphocytes. However, optimal loading conditions have still to be defined. DCs were pulsed either with tumor lysates, apoptotic or necrotic preparations of a breast cancer cell line and subsequently used to stimulate autologous T-lymphocytes. Antigen loading was quantified using immunofluorescent-based methods. Four hours co-incubation of apoptotic TCs or tumor lysates with DCs undergoing maturation resulted in effective DC-loading. However, the DCs pulsed with apoptotic TCs were best in stimulating interferon-gamma (INF-gamma) secretion as the effector function of autologous T-cells. Tumor lysates are in common use for DC-based vaccine manufacturing. However, our data indicate an advantage of apoptotic TC-preparations in regard to antigen loading effectiveness as well as the loaded DC's capacity to activate T-cells.