In the present study we have successfully isolated neuroblastoma cells from primary human neuroblastoma tissues by using a magnetic bead-mediated purification system. Since primary neuroblastoma tissues contained CD3- and CD19-positive lymphocytes, total cell suspensions were prepared and incubated with magnetic beads coated with anti-CD3 or with anti-CD19 antibody. After magnetic separation, unbound materials were recovered and analyzed by immunohistochemical staining for NB84, one of the neuroblastoma markers. Immunohistochemical and FACS analyses demonstrated that NB84-positive cells were enriched in the unbound fraction. Subsequently, unbound materials were seeded on cell culture plates and maintained at 37 degrees C overnight. After incubation, non-adherent cells were collected and stained with anti-NB84 antibody. Under our experimental conditions, a significant increase in the number of NB84-positive cells was observed. Furthermore, our purified NB84-positive cells responded to all-trans retinoic acid and nerve growth factor better than the initial primary cells. Collectively, our present results suggest that magnetic bead-mediated purification enriches neuroblastoma cells which retain their biological properties.