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Background: The deposition of protein Z was investigated in atherosclerotic vascular lesions of patients with diabetes mellitus or atherosclerotic vascular disease without diabetes in comparison to controls., Patients and Methods: Protein Z antigen was evidenced by immunohistochemistry in arteries of 5 healthy control patients, 11 diabetic patients with arterio-occlusive disease and 7 patients suffering from arterio-occlusive disease without diabetes. For immunohistochemistry, a commercially available antibody was taken as first antibody, and immunopositivity was evaluated independently by two investigators (J.G.; I.K.) as negative (0), positive (+) and strongly positive (++). The results were assessed by the Whitney-Mann-Wilcoxon test., Results: Macrovascular endothelial cells were stained positive for protein Z in all arteries studied. Arteries of controls did not show significant immunopositivity in cells other than macrovascular endothelial cells, while the microvascular endothelial cells of control arteries were largely negative. The proliferating subendothelial space in atherosclerotic vascular lesions showed significant immunopositivity for protein Z. In contrast to control arteries, the microvascular endothelial cells of the proliferating areas stained positive. The staining pattern of the subendothelial space was similar in atherosclerotic vessels independent of the risk factor for atherosclerosis. Plaques were immunopositive for protein Z, too., Conclusions: Protein Z is present in atherosclerotic vascular lesions of diabetic and non-diabetic patients, but not in the subendothelial space and microvascular endothelial cells of healthy controls. Since protein Z-positivity was detected in microvascular endothelium as well as in extra-vascular deposits around plaques, it may play a role in the development of these lesions.

Background: Cellular actions of advanced glycation end-products (AGE) are mediated by a receptor for AGE (RAGE), a novel integral membrane protein. Immunohistochemical studies show only low-level RAGE antigen expression in endothelial cells. Design. It was the purposes of the study to compare expression of RAGE antigen by endothelial cells in non-diabetic uraemic patients (n=8) with non-uraemic controls (n=11). Samples of arterial tissue were obtained at the time of renal transplantation (in uraemic patients) and abdominal surgery (in controls). RAGE antigen was visualized using guinea-pig anti-RAGE IgG and PAP technique., Results: Marked staining for RAGE was noted in endothelial cells, both arterial endothelium and endothelium of vasa vasorum of normoglycaemic uraemic patients, but was not demonstrable in endothelial cells of large arteries and only faintly expressed in vasa vasorum of non-uraemic individuals., Conclusion: Normal endothelial cells do not constitually express RAGE antigen; in contrast it is expressed by arterial and capillary endothelial cells of uraemic patients. The observation is of note in view of the putative role of AGE of causing atherosclerotic and non-atherosclerotic vascular lesions.