UNMYELINATED NERVE-FIBER ESTIMATION BY IMMUNOCYTOCHEMISTRY - CORRELATION WITH ELECTRON-MICROSCOPY

Electron microscopy (EM) is currently required for quantitation of unm yelinated nerve fiber (UMNF) densities. Electron microscopy is time-co nsuming, costly, and generally only considers a fraction of an entire nerve. Anti-PGP 9.5, which recognizes a neuron-associated antigen, may be used in glutaraldehyde-fixed, paraffin-embedded human sural nerve biopsies to identify unmyelinated axons. In nerves counterstained with Luxol fast blue, the correlation between EM-obtained UMNF densities a nd paraffin-obtained UMNF densities was excellent (p < 0.0001). In add ition, myelinated nerve fiber (MNF) densities estimated by the same me thod from paraffin-embedded nerve gave excellent correlation with trad itional morphometric estimates (p = 0.0026). PGP 9.5 immunocytochemist ry enables the detection of minute axons (<0.5 mu m) and multiple axon s per Schwann cell subunit, but does not allow for the preparation of accurate fiber size histograms or the analysis of UMNF pathology. Whet her used for UMNF quantitation or as a qualitative review df the UMNF population of a nerve, this method is quicker and less expensive than traditional EM methodologies;