IMMUNOLOGICAL RELATIONSHIPS OF NGF, BDNF, AND NT-3 - RECOGNITION AND FUNCTIONAL INHIBITION BY ANTIBODIES TO NGF

Polyclonal antibodies raised against mouse 2.5S NGF (mNGF) and against synthetic peptides made from hydrophilic portions of mNGF have been u sed to compare the immunological properties of mNGF, human recombinant brain-derived neurotrophic factor (hrBDNF), and human recombinant neu rotrophin-3 (hrNT-3). Affinity-isolated antibodies raised against inta ct mNGF reacted with all three neurotrophins when tested by ELISA and totally or partially blocked the bioactivities of the proteins in surv ival assays of embryonic chicken sensory and sympathetic neurons. On W estern blots, mNGF antibodies reacted with all three neurotrophins but less well with hrBDNF and hrNT-3 than with mNGF. Antibodies to hydrop hilic peptides within NGF (amino acids 23-35, 59-67, 69-79, and 91-100 ) showed partial reactivity with some but not all of the neurotrophins when tested by ELISA and on Western blots. The peptide antibodies wer e also selectively effective in reducing the survival-promoting activi ty of the neurotrophins on sensory neurons. Results show that mNGF, hr BDNF, and hrNT-3 are immunologically related proteins and that mNGF an tibodies react also with other members of the neurotrophin family.