Toxic epidermal necrolysis is a life-threatening disease, the pathogenesis of which remains largely unknown. Histologically, in addition to the characteristic epidermal alterations, there is a sparse mononuclear cell infiltrate in the dermis. The immunologic characteristics of this infiltrate are not well known. In a case of drug-induced toxic epidermal necrolysis with fatal outcome in a 48-year-old man, we demonstrated that the majority of the inflammatory cells were of helper/inducer T-lymphocyte subsets, having only a minority of cytotoxic/suppressor T-lymphocytes and rare cells with natural killer cell phenotype. The significance of these observations is discussed, with reference to the occurrence of lesions at epithelial sites bearing local networks of antigen-presenting cells (Langerhans' cells).
Nonenzymatic glycosylation of proteins of the erythrocyte membrane was determined by incubating erythrocyte ghosts with [3H]borohydride. The incorporation of tritium into protein provides a reliable assay of ketoamine linkages. The membrane proteins from 18 patients with diabetes incorporated twice as much radioactivity as membrane proteins from normal erythrocytes. After acid hydrolysis, amino acid analysis showed that the majority of radioactivity was localized to glucosyllysine. Autoradiograms showed that all of the major proteins of the erythrocyte membrane, separated by electrophoresis on sodium dodecyl sulfate gels, contained ketoamine linkages. No protein bands in either normal or diabetic erythrocytes showed significant preferential labeling. Erythrocyte membranes from three patients with hemolytic anemia showed reduced incorporation of tritium from [3H]-borohydride, indicating decreased nonenzymatic glycosylation. Two patients with diabetes and hemolytic anemia had incorporation of radioactivity similar to that of normal individuals. In these groups of patients the incorporation of tritium into erythrocyte membrane proteins correlated with levels of hemoglobin AIc. Thus the modification of membrane proteins like that of hemoglobin depends on blood glucose levels as well as erythrocyte age. These studies show that the enhanced nonenzymatic glycosylation of proteins in diabetics extends beyond hemoglobin to the proteins of the erythrocyte membrane and probably affects other proteins that have slow turnover and are exposed to high concentrations of glucose.
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