A monoclonal antibody modulates the interaction of nerve growth factor with PC12 cells

A nerve growth factor (NGF) receptor interactive monoclonal antibody (192-IgG) which enhances beta-NGF binding to PC12 cells has been produced. The hybridoma clone was obtained by fusing Sp2/0- Ag14 myeloma cells with splenocytes from Balb/C mice which had been immunized with n-octyl glucoside solubilized proteins from isolated PC12 cell plasma membranes. The antibody is an IgG, which does not bind beta-NGF. It binds to the same number of sites on PC12 cells at low temperature as does beta-NGF. The 192-IgG increases the apparent affinity of beta-NGF binding to fast receptors on PC12 cells at low temperature by a factor of 2.5- to 4-fold and enhances the photoactivatable cross-linking of beta-NGF to the same receptor while decreasing the cross-linking of beta-NGF to the slow NGF receptor. At 37 degrees C 192-IgG partially inhibits the regeneration of neurites from primed PC12 cells. The 192-IgG also reduces the rate of appearance of binding to slow NGF receptors and increases the proportion of beta-NGF bound to fast receptors at 37 degrees C. These results implicate the slow receptor as the mediator of the biological response. This antibody provides a tool for examining steps in the mechanism of action of beta-NGF after binding to the receptor.