Significance of lymphocytes and blood vessel changes for edema formation in polyradiculoneuritis

Human sural nerve biopsies of eight cases with acute, subacute and chronic polyradiculoneuritis were studied by means of immunohistochemistry to characterize the inflammatory infiltrates. In addition, the structural changes of the endoneurial blood vessels were examined by electron microscopy, since both factors are likely to contribute to disturbances of the blood-nerve barrier. By use of six monoclonal antibodies, it was shown that the inflammatory infiltrates in cases with more acute polyradiculoneuritis are predominantly recruited by Leu 3a- and Leu 4-positive T lymphocytes. In more chronic polyradiculoneuritis beside of few Leu 3a-positive and Leu 4-positive T lymphocytes also B cells occurred. Leu M3-positive macrophages were detected in all cases with fluoride myelin degeneration. Since immunoreactivity for antigens of the HLA-D-locus (Leu-HLA-DR and Leu 10) were present on the infiltrating mononuclear cells, it can be postulated that they represent active and immunocompetent cells. Ultrastructurally, the amount of pinocytotic vesicles in the endothelial cells of the endoneurial blood vessels was increased. Moreover, a prominent folding of the luminal and abluminal surface of vascular endothelial cells and diminution of the intercellular tight junctions were observed. These findings appear suitable to explain the increased leakage of serum proteins across the blood-nerve barrier in polyradiculoneuritis sharing general features of cell-mediated immunity.