Developmentally regulated epitopes on a neurofilament protein visualized by monoclonal antibodies

Two monoclonal antibodies (mabs) which recognized the 68 kDa subunit of the rat neurofilament triplet were isolated. In immunoblots with SDS-solubilized and reduced proteins, these mabs recognized their epitopes equally well in embryonic and in adult tissue. However, these epitopes were developmentally regulated in paraformaldehyde-fixed rat brain sections. They were abundant in all compartments of differentiating neurons, whereas in mature neurons their presence was markedly attenuated, with a moderate abundance in perikarya and larger dendrites and low concentrations in axons. Thus, a differential developmental modification, possibly involving the masking of an epitope, is demonstrated for the small neurofilament polypeptide in rat and monkey brain tissue.