Nerve growth factor receptors on dissociated neurofibroma Schwann-like cells

Neurofibromatosis is a disorder which predominantly involves cellular elements of peripheral neural sheaths. Little is known about the regulation of differentiation and proliferation of cells comprising neurofibromas. Because nerve growth factor-like activity may be present in neurofibromas and the cells comprising neurofibromas are neural crest derivatives, we have investigated whether nerve growth factor (NGF) receptors are present on cells from dissociated dermal neurofibromas. Using 125I-NGF to measure binding to cultured cells in suspension and for autoradiography, we identified a population of cells having characteristics of Schwann cells which exhibited saturable 125I-NGF binding. This binding is characteristic of the "fast" (low affinity) NGF receptor, having a Kd of approximately 1 nM and a Bmax of at least 120 fmol/10(6) cells. Less than 20% of the bound 125I-NGF (5 ng/ml) is not displaced when transferred to 0 degrees C by an excess of unlabeled NGF (10 micrograms/ml) and is therefore bound to either "slow" (high affinity) sites or is rapidly internalized. NGF receptors with characteristics of fast sites have recently been reported on Schwann-like cells from chick dorsal root ganglia [Zimmerman, A., and Sutter, A. Beta nerve growth factor (beta NGF) receptors on glial cells. Cell-cell interaction between neurones and Schwann cells in culture of chick sensory ganglia. EMBO J., 2: 879-885, 1983]. The identification of NGF receptors on both fetal chick dorsal root ganglia and neurofibroma Schwann-like cells suggests that NGF may have a role in the regulation of Schwann cell function in both normal development and in neurofibromatosis.