Phenotypic and proliferative properties of Schwann cells from nerves of diabetic patients.

The phenotypic (morphologic and antigenic) properties and mitotic index of cultured Schwann cells obtained by dissecting nerves from six diabetic patients were studied. These features were compared with those of Schwann cells cultured in vitro from six normal control nerves. Preservation of the specific antigenic properties of cells, identified with rabbit antiserum as bovine protein S-100, was documented by immunofluorescence with monoclonal antibodies against laminin, fibronectin, histocompatibility antigens HLA-A, B, C and -DR, HNK-1 antigen and the human receptor for nerve growth factor. The cell proliferation index was assessed by incorporation of bromodeoxyuridine. The results of the study showed that the mitotic capacities of Schwann cells from diabetic nerves cultured in vitro remained comparable with those of normal control cells. As regards phenotypic characteristics, no modifications were detectable by immunofluorescence. These findings suggest that the phenomena of demyelination and remyelination, sometimes with onion bulb features, which can be observed in some cases of diabetic neuropathy, are not due to a primary dysfunction of the Schwann cells but are secondary to axonal degeneration.

Sural nerve immunoreactivity for nerve growth factor receptor in a case of localized hypertrophic neuropathy.

Immunoreactivity for nerve growth factor receptor (NGFR) was examined using a monoclonal antibody against human NGFR in the sural nerve of a 24-year-old woman, affected by localized hypertrophic neuropathy (LHN). NGFR expression was correlated with electron microscopy and with immunoreactivity for S-100 protein, laminin, HLA-DR, HNK-1, P0 glycoprotein and neurofilament peptides. Our results indicate that in LHN most of whorl-forming cells are NGFR positive and S-100 protein or HLA-DR negative. These data along with the ultrastructural features suggest their origin from perineurium.

Quantitative assessment of class II molecules in normal and pathological nerves. Immunocytochemical studies in vivo and in tissue culture.

We have analysed class II molecules (HLA-DR) expression in human fetal nerves at different stages of gestation, in human control nerves and in nerves of patients with peripheral neuropathies of different aetiology. Immunochemical demonstration of HLA-DR antigens was also performed on isolated human Schwann cells at different times in culture, from the same nerves. In normal nerves, HLA-DR positive material is localized only on endothelial and perivascular cells and in rare perineurial and endoneurial cells. In fetal nerves, HLA-DR positive material is already present by the sixteenth week of gestation. Quantitative analysis of HLA-DR molecules density in pathological nerves showed a wide heterogeneity in different neuropathies with no correlation between the type of pathology and the intensity and pattern of staining. Cultured human Schwann cells obtained from fetal, normal adult and pathological (vasculitic neuropathy) nerves were HLA-DR positive and the percentage of positive cells increased with time in culture. DR antigen appearance on human Schwann cells may reflect not only an immunologically-mediated phenomenon but also a dependence on axon-Schwann cell interaction.

The ontogenesis of Fc gamma receptors and complement receptors CR1 in human peripheral nerve.

The ontogenesis of Fc gamma receptors (FcR) and C3b/C4b receptors (CR1) was studied in peripheral nerves from ten fetuses aged from 20 to 38 weeks using immunohistochemical and functional assays. Monoclonal antibodies (mAbs) against FcR and CR1 stained nerve fibers at 10 weeks of gestation and the staining intensity increased during nerve maturation. FcR and CR1 are probably expressed on Schwann cells and are early markers during the development of peripheral nerves. Functional FcR activity was detected in nerve sections before initiation of myelination, which occurs at approximately 18-19 weeks, whereas functional CR1 activity was found in the sections after myelination. Functional CR1 activity may, therefore, be related to myelin. The ontogenesis of FcR and CR1 was also studied on Schwann cells in culture from three fetuses aged 14, 16 and 19 weeks, using immunofluorescence technique with mAbs. The FcR and CR1 are lost on cultured Schwann cells. This suggests that the receptors are not intrinsic to the cells or that Schwann cells require axonal contact for the expression of FcR and CR1.

Human Schwann cells: cytochemical, ultrastructural and immunological studies in vivo and in vitro.

Cytochemical, ultrastructural and immunological properties of human Schwann cells were studied in normal adult and foetal nerve sections and in tissue cultures. As specific markers for Schwann cells we used S-100 protein and laminin. The presence of Sudan black-positive, Oil Red-O-negative material was found in Schwann cells in vitro. Structural features, examined at E.M. level, are described. This information may be useful in nerve tissue culture studies, a new tool for the investigation of dyschwannian neuropathies.