Precise ultrastructural localization of endothelial leukocyte adhesion molecule-1, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 in patients with IgA nephropathy

Using light and electron microscopy, we performed an immunohistochemical study of endothelial leukocyte adhesion molecule-1 (ELAM-1), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) in 15 patients with IgA nephropathy to clarify the localization of these adhesion molecules. The normal portions of 2 kidneys removed due to localized carcinoma and 3 biopsies from patients without glomerular disease were used as a control. By light microscopy, ELAM-1, VCAM-1, and ICAM-1 all showed positive staining in IgA nephropathy, with the intensity of staining following the sequence ICAM-1 > VCAM-1 > ELAM-1. ELAM-1 and VCAM-1 showed a patchy distribution of moderate staining in the tissues, including the mesangium, crescents, adhesions, and tubules. In contrast, there was marked linear ICAM-1 staining throughout the vascular walls. ELAM-1 and VCAM-1 were positive on the basolateral surfaces of a few proximal tubular epithelial cells in association with inflammatory cell infiltration, while ICAM-1 was found on the brush border. ICAM-1 was positive in the glomerular capillary walls and interstitial vessels of the control kidney tissue, while ELAM-1 and VCAM-1 were virtually absent. By electron microscopy, ELAM-1 positivity on the urinary surface of the parietal/visceral epithelial cells was often associated with adherent mononuclear cells in the urinary space. VCAM-1 positivity was increased in the perinuclear space and/or cytoplasm of mesangial cells as well as at the mesangial cell-endothelial cell interface. These findings suggest that ELAM-1 and VCAM-1 may be more closely related than ICAM-1 to the major histopathological changes occurring in IgA nephropathy, including mesangial expansion, formation of crescents and adhesions, and tubulointerstitial injury.