Neurofilaments (NFs) are intermediate filaments essential for providing structural support to neurons, particularly within axons. They play a crucial role in maintaining axonal diameter, which directly influences nerve conduction velocity (1). Neurofilaments are composed of three primary subunits - NF-L (light), NF-M (medium) and NF-H (heavy) – along with an NF-associated protein. In the adult central nervous system (CNS), α-internexin serves as the fourth neurofilament subunit, whereas in the peripheral nervous system (PNS), peripherin takes on this role (2).
Beyond their structural function, neurofilaments are also valuable biomarkers in both research and clinical settings. They are widely used in immunohistochemistry to stain and visualize axons, particularly in peripheral nerves and the CNS. Increased levels of neurofilament proteins in cerebrospinal fluid (CSF) or blood are strongly associated with neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and Alzheimer’s disease (3). In peripheral nerve studies, neurofilament staining is often combined with other markers, such as S100, to provide a more comprehensive assessment of nerve structure and pathology (4).