Distinction between nerve growth factor and glial factor

Abstract

THE morphogenesis of individual cell types can be studied in tissue culture: for example neuroblastoma cells can be induced to differentiate by a macromolecular factor released by cultured glioma cells¹. On the other hand, survival and process formation in cell cultures of dissociated ganglia from embryonic chicks, newborn mice or rats require the presence of nerve growth factor^2,6. An enriched population of non-neuronal cells can replace NGF in these systems and their effect can be impaired by addition of anti-NGF antibody^2,3. The fact that NGF has been detected in the homogenate of solid tumours induced by subcutaneous injection of glioma cells previously grown in culture, and that a partially purified fraction of this homogenate induces morphological differentiation in neuroblastoma cells⁴ suggests that NGF and glial factor are the same molecule. We present evidence that NGF and glial factor are molecules with different properties and distinct specificities.