Figure 1. Whole tumor-cell vaccination early after allogeneic stem cell transplantation. Subcutaneously injected irradiated autologous cancer cells provide a source of tumor antigens at the vaccination site (1). Granulocyte macrophage colony-stimulating factor (GM-CSF) secreted by irradiated bystander cells stimulates the recruitment, maturation and immunostimulatory activity of dendritic cells (DCs) at the vaccination site (2). The allograft contains hematopoietic precursor cells and mature T cells, which might be tumor-reactive, alloreactive or non-alloreactive. Early after allogeneic stem cell transplantation (allo-HSCT), homeostatic cytokines support T cell expansion in the lymphopenic host (3). Autologous whole tumor cell-based vaccination may tip the balance between leukemia-specific and alloreactive T cell responses in favor of a graft-vs.-leukemia (GvL) effect. GvHD, graft-vs.-host disease; s.c., subcutaneous; i.d., intradermal.