Abstract Dendritic cells (DC) are capable of capturing and processing antigens and can stimulate co-cultured effector cells in a specific manner. Here, we pulsed DC with apoptotic bodies (apb) from colorectal carcinoma. For enhancement of the immunogenic potential of apb, we transduced the tumor cells with the MHC class II gene before irradiation. After transfection, tumor cells, which are normally MHC class II negative, expressed MHC class II in 26.3%. Staining apb with PKH-2 and DC with PKH-26, we determined an apb-uptake of 27.6% by DC. Lytic activity of effector cells cocultured with DC pulsed with MHC class II transduced apb against the donor cell line at an effector to target ratio of 40:1 was 43.8% compared to 35.3% for pulsing with mock transduced cells. Secretion of interleukin-12 (IL-12) by DC was significantly enhanced after pulsing with MHC class II transduced apb compared to DC pulsed with mock transduced apb. Coculture with apb-pulsed DC led to an increase of proliferation rate and can stimulate effector cells in a specific manner. The immunogenic potential could be enhanced by transducing tumor cells with the MHC class II gene.