Characterization of human nerve basal lamina for their binding properties of anti-MAG antibodies

The functional importance of the basal lamina in Schwann cell development and in adult peripheral nerve fibers is well known. We have demonstrated previously by confocal microscopy that IgM deposits are present on the basal lamina of myelinating Schwann cells of nerve biopsies from patients with an anti-MAG IgM neuropathy. Therefore, the basal lamina was postulated to represent an early target for the uptake of autoantibodies on the surface of myelinated nerve fibers. In this study, the preparation of cell- and myelin-free basal lamina from human peripheral nerves, using a detergent-dependent method is described and characterized by immunohistochemical and biochemical analysis. Using these methods we demonstrated that an enrichment of basal lamina components of Schwann cells with extraction of myelin could be achieved. Western blot analysis and immunohistochemical characterization showed that anti-MAG IgM antibodies did not recognize an epitope on the basal lamina of normal nerves. The established method will allow in situ investigations of basal lamina components from human peripheral nerves in health and in disease, e.g. peripheral neuropathies of infectious or inflammatory origin.