An anti-GD2 ganglioside human/mouse chimeric monoclonal antibody, ch14.18, like its murine counterpart, 14.G2a, was shown to bind to human neuroblastoma cells. This chimeric antibody proved to be more effective than 14.G2a in mediating the lysis of neuroblastoma cells with human effector cells, such as granulocytes and natural killer cells within the peripheral blood mononuclear cell population. A comparison of these two effector cell populations isolated from the same donor revealed granulocytes to be more effective than peripheral blood mononuclear cells in lysing neuroblastoma cells, which were coated with monoclonal antibody ch14.18. Addition of recombinant human granulocyte-macrophage colony-stimulatory factor increased ch14.18-mediated lysis of neuroblastoma cells by granulocytes but not by peripheral blood mononuclear cells. In fact, granulocytes were effective in mediating lysis of neuroblastoma cells coated with ch14.18 irrespective of whether they were obtained from normal adults or from neuroblastoma patients.