CULTURE OF HUMAN INSULINOMA CELLS - DEVELOPMENT OF A NEUROENDOCRINE TUMOR CELL-SPECIFIC AND HUMAN PANCREATIC-ISLET CELL-SPECIFIC MONOCLONAL-ANTIBODY

We report on the culture of human insulinoma cells derived from a 32-y ear-old male patient with hyperinsulinism due to an insulinoma of tile pancreas. single-cell suspension was made by passing insulinoma fragm ents through a fine-gauge stainless-steel mesh. Cluster-forming insuli noma cells resembling pancreatic islets grew in the presence of fibrob lasts. The insulinoma cell clusters could be differentiated from fibro blasts by using in situ pan optic staining and specific immunocytochem ical staining (anti-human insulin and anti-human insulinoma monoclonal antibody (mAb) D24). mAb D24 was generated using insulinoma cells as antigen for immunization of a Balb/C mouse and cell fusion by the hybr idoma cell technique. The anti-insulinoma cell mAb recognized a 32 kDa protein on immunoblot analysis of neuroendocrine tumor cells. D24 mAb also reacted immunohistochemically with normal pancreatic beta-cells and tumors such as vipoma, gastrinoma and carcinoid. Insulinoma cell c lusters separated from fibroblasts by micromanipulation and plated int o multiwell culture dishes exhibited an insulin-secretion rate of simi lar to 30 U/100 cells per 24 h with no insulin-secretory response to e levated glucose concentration. Purified insulinoma cells incubated wit h 1 ng/ml human nerve growth factor expressed neurofilament and neurit e extension. These findings together with earlier observations in anim al models suggest that human pancreatic beta-cells share some properti es with neurons and are related to other neuroendocrine cells in the g astrointestinal tract.