Antibodies to neuron-specific enolase for the delineation of the entire diffuse neuroendocrine system in health and disease.

A very widely distributed system containing regulatory peptides has recently been discovered. These active peptides are localized to typical endocrine cells and nerves of the so-called diffuse neuroendocrine system. Investigation of the entire system was, until recently, very difficult, as existing techniques (including histochemistry, electron microscopy, and peptide immunocytochemistry) only partly visualized its components. Neuron-specific enolase is a soluble isomer of a glycolytic enzyme enolase that was first discovered in the brain and localized exclusively to neurons, hence its name. Antibodies to neuron-specific enolase are now known to immunostain the entire diffuse neuroendocrine system of every organ of the body. Thus, all endocrine cells and nerves containing the recognized regulatory peptides, as well as amines and classical neurotransmitters like acetylcholine and noradrenaline, contain significant quantities of immunostainable neuron-specific enolase. Therefore, these antibodies, which can be used on routinely fixed tissue, allow the visualization of the entire diffuse neuroendocrine system. Furthermore, all classes of neuroendocrine neoplasms, as well as the pattern of normal or abnormal innervation, can easily be marked by immunostaining of neuron-specific enolase.