Generation of a monoclonal antibody against the myelin protein CNP (2',3'-cyclic nucleotide 3'-phosphodiesterase) suitable for biochemical and for immunohistochemical investigations of CNP.

The functional role of CNP (2',3'-cyclic nucleotide 3'-phosphodiesterase), a minor component of central and peripheral myelin is still unclear. Here we describe preparation of a monoclonal antibody directed against CNP. The antibody, of the immunoglobulin IgG1 type, raised with a basic 46 kDa membrane-associated protein solubilized from pig cerebellar membranes, can be used to detect immunoreactivity in solubilized brain homogenates from pig, mouse, rat, sheep, cow and man, in cerebrum and cerebellum, but not in other tissues such as liver, skeletal and heart muscle. The antibody recognizes the CNP doublet band and shows no cross-reactivity with any of the other brain proteins solubilized. In tissue sections from paraformaldehyde-fixed rat brain the antigen was localized in oligodendrocytes. In cultured glial cells from newborn mice the antibody stained cells which were identified as oligodendrocytes by co-localization of myelin basic protein. Even cells from a C6 rat glioma cell line, which contain very little of CNP, were labeled by the monoclonal antibody. Thus the monoclonal antibody recognizing CNP from several species is suitable for immunocytochemical investigations and also for biochemical studies of CNP, since the antibody has been employed for immunoprecipitation and immunopurification of CNP in crude brain homogenates.