NCAM EXPRESSION IN THE PULMONARY NEURAL AND DIFFUSE NEUROENDOCRINE CELL SYSTEM

Neural cell adhesion molecule (NCAM)-a membrane protein involved in ce ll-cell adhesion within the central and peripheral nervous systems-was demonstrated to be a sensitive and specific marker for neuroepithelia l bodies (NEB) and neural tissue elements in the cat lung. Using the s treptavidin-biotin immunoperoxidase method, NCAM reactive sites were i nvestigated with monoclonal and polyclonal antibodies on serial sectio ns of Bouin fixed, paraffin embedded lung tissue. Moreover, NCAM expre ssion was compared with that of neuron-specific enolase (NSE) on adjac ent sections. The most obvious NCAM staining was obtained with the mon oclonal antibody. From newborn to adult life, cell surface labeling wa s identified on NEB cells. In mature cat lung, they were no longer pos itive. Solitary neuroendocrine cells (NEC) were always negative. In co ntrast to the transient postnatal immunoreactivity of NEB cells, nerve fibers and ganglion cells were stained throughout all life stages stu died. The distribution of NCAM in NEB, nerve fibers and ganglion cells was similar to that of NSE, except in the adult lung. This study reve als that during lung growth shared NCAM antigens exist between the pul monary nervous and endocrine system, whereas in mature lung NCAM prote ins are confined to neural tissue elements. The difference in NCAM exp ression between NEB and NEC might suggest an involvement of NCAM in th e formation of contacts between NEB cells and nerves. (C) 1997 Wiley-L iss. Inc.