Neurofilament and intermediate filament immunoreactivity in human intestinal myenteric neurons

It has been reported previously that rat myenteric neurons have neurofilament (NF) immunoreactivity that differs from the brain. Now the result of a study of neurofilaments and intermediate filament immunoreactivity in human colon and ileum using a panel of antibodies and indirect immunofluorescence techniques is reported here. Results with polyclonal neurofilament antisera showed positive immunoreactivity in subsets of myenteric neurons. Results with peripherin and alpha-internexin showed immunoreactivity in some neurons that contained neurofilaments and in many that were neurofilament negative, similar to our observations in rat. Some monoclonal antibodies to epitopes on NF-M and NF-H demonstrated weak or negative immunoreactivity in human myenteric neurons yet showed positive immunoreactivity in brain. Some of these antibodies are phosphorylation dependent, suggesting NF-M and NF-H epitopes in myenteric neurons are not as phosphorylated as in brain; other antibodies are phosphorylation independent, suggesting other differences or masking of epitopes. In summary, neurofilaments are present in a subset of myenteric neurons. In those human myenteric neurons that contain them, the neurofilaments appear immunologically distinct from those in the brain.