1. ¹INSERM UMR S 702, Paris, France
2. ²Université Pierre et Marie Curie, Paris, France
3. ³Département de Nephrologie, Paris, France
4. ⁴Institut de recherche en néphrologie et transplantation d'Ile de France, Hôpital Henri Mondor, Université Paris 12, Paris, France
5. ⁵Département de Nephrologie, Hôpital Tenon, Assistance-Publique Hôpitaux de Paris, Paris, France

Correspondence: H Debiec, INSERM U702, Hôpital Tenon, 4 rue de la Chine, Paris 75020, France. E-mail: hanna.debiec@chusa.jussieu.fr

⁶Current address: Département de Pathologie, Hôpital Henri Mondor, Créteil, France.

Received 26 January 2007; Revised 20 September 2007; Accepted 25 September 2007; Published online 5 December 2007.

Abstract

The L1 cell adhesion molecule (CD171) is a multidomain membrane glycoprotein of the immunoglobulin superfamily. We evaluated its expression in human acute kidney injury and assessed its use as a tissue and urinary marker of acute tubular injury. Using immunohistochemical studies with antibodies to the extracellular or cytoplasmic domains, we compared L1 expression in normal kidneys in 24 biopsies taken from patients with acute tubular necrosis. L1 was found at the basolateral and the lateral membrane in all epithelial cells of the collecting duct in the normal kidney except for intercalated cells. In acute tubular necrosis, L1 lost its polarized distribution being found in both the basolateral and apical domains of the collecting duct. Further, it was induced in thick ascending limb and distal tubule cells. Apically expressed L1 found only when the cytoplasmic domain antibody was used in biopsy specimens of patients with acute tubular necrosis. The levels of urinary L1, normalized for creatinine, were significantly higher in all 24 patients with acute tubular necrosis compared to five patients with prerenal azotemia or to six patients with other causes of acute kidney injury. Our study shows that a soluble form of human L1 can be detected in the urine of patients with acute tubular necrosis and that this may be a marker of distal nephron injury.