ANTI-NKH-1 ANTIBODY SPECIFICALLY STAINS UNMYELINATED FIBERS AND NON-MYELINATING SCHWANN-CELL COLUMNS IN HUMANS

Anti-NKH-1 antibody recognizes an isoform of the neural cell adhesion molecule (N-CAM) that is involved in cell-cell interactions during emb ryonic stages and has been detected in skin autonomic nerves. The spec ificity of anti-NKH-1 antibody for human unmyelinated fibres (UF) and the distribution of the antigens recognized by this antibody at the ul trastructural level, were evaluated by immunohistochemistry and immuno electron microscopy on nerve biopsy samples from patients with normal nerve biopsies and a variety of peripheral neuropathies. The anti-NKH- 1 antibody strongly stained all unmyelinated firbres while no myelinat ed fibre was stained. Autonomic nerve fibres were visualized at the pe riphery of blood vessels. Immunoelectron microscopy showed that the an tigen recognized by the antibody was located at Schwann cell-axon inte rfaces and in portions of joined Schwannian surfaces, i.e. along mesax ons of non-myelinating Schwann cells. Expression of NKH-1 was basicall y similar in normal and diseased nerves as expression of NKH-1 was sim ilar at the level of apposed plate-like Schwann cell processes than al ong normal mesaxons. The extent of labelling of diseased nerves by the anti-NKH-1 antibody likely depended on the number of residual Schwann cell columns observed by light microscopy.