Abstract
Two hybrid cell lines, MC beta-1 and MC beta-2, secreting monoclonal antibodies against mouse submaxillary gland beta nerve growth factor (beta NGF), were produced by interspecies hybridization of spleen cells from rats immunized with beta NGF and mouse myeloma cells. The antibodies secreted by the two hybridomas are of the IgG1 subclass and bind staphylococcal protein A. The equilibrium dissociation constant of the beta NGF--antibody complex was determined for the MC beta-1 antibodies in solid phase and in solution. On protein A-coated surfaces the Kd is 3 X 10(-10) M, 2 orders of magnitude lower than the Kd 2 X 10(-8) M obtained in solution. The antigenic site recognized by MC beta-1 antibodies is present on each protomer of the beta NGF dimer, and the binding affinity of the second antibody molecule is similar to that of the first. The MC beta-1 antibodies inhibit neurite outgrowth from sensory neurons. Because this inhibition directly correlates with the inhibition of binding to the higher affinity beta NGF receptors, it suggests that beta NGF complexed with two antibody molecules does not bind to the receptor and is biologically inactive.