Expression of the 4C5 antigen during development and after injury of the rat sciatic nerve.

We have previously reported the production of monoclonal antibody 4C5 that recognizes a cell surface neuron specific antigen, the 4C5 antigen (Thomaidou and Patsavoudi: Neuroscience 53:813-827, 1993). Antibody perturbation experiments have suggested that the 4C5 antigen is involved in granule cell migration processes in vitro (Thomaidou et al: J Neurochem 64:1937-1944, 1995). In the present study, we have used monoclonal antibody 4C5 to investigate the cellular distribution and the expression of the corresponding antigen during development, and after injury of the rat sciatic nerve. Immunocytochemistry revealed presence of the protein both in myelin and non-myelin forming Schwann cells. Western blot analysis showed that monoclonal antibody 4C5 recognizes the same 94 kdalton polypeptide in the sciatic nerve as in the brain. Immunocytochemical analysis revealed an age-dependent decline of the 4C5 antigen expression. Moreover, following adult sciatic nerve crush, 4C5 immunoreactivity becomes intense in Schwann cells of the distal segment, as early as 4 days after injury and remains at relatively high levels up to 2 weeks after the crush. By the 3rd week, 4C5 immunoreactivity is greatly reduced, and by the 4th week it is hardly detectable. Our results concerning the cellular localization and temporal expression of the 4C5 antigen during development and after injury of the rat sciatic nerve, suggest that it may participate in Schwann cell migrations that occur during such processes.