[16] Derivation of monoclonal antibody to nerve growth factor

Nerve growth factor (NGF) is essential for the differentiation of the neural crest during development and is required for the maintenance of sympathetic and sensory neurons in culture and in vivo. Although NGF is not a mitogen, it shares many features with epidermal growth factor, insulin, and other protein hormones, such as interaction with a plasma membrane receptor, internalization, and pleiotropic signals to the target neuron. The procedures described in the chapter demonstrate that the problems inherent in production of monoclonal antibodies and immunological studies with mouse NGF can be essentially overcome in several effective ways. The results from species specificity analysis and from the variety of effects of 12 antibodies on the bioassay suggest that there are at least 3 epitopes on the 13,000-DaβNGF, one or more of which are shared with other species. Binding and bioassay analysis present a consistent thermodynamic picture. A sensitive and highly specific immunoassay utilizing these monoclonal antibodies has not yet been reported, but could be readily developed from the radioimmunoassay (RIA) or enzyme linked immunosorbent assay (ELISA) techniques already described or further refined by incorporation of the two-site RIA described for polyclonal antibodies. These reagents should also be useful for affinity purification of NGF and for immunocytochemistry. More insight into the biochemistry of the NGF molecule, its interaction with responsive neurons, and its biological effects during development should be provided with these monoclonal antibodies.