Analysis of adhesion molecule expression by tubular epithelial cells using urine immunocytology

On their surface, renal tubular cells present intercellular adhesion molecule-1 (ICAM-1) during acute renal allograft rejection. We propose that the extent of ICAM-1 expression by renal tubular cells can be estimated from urine immunocytology. To test this hypothesis, we obtained 52 samples of urine from 31 renal transplant recipients with either acute tubular necrosis, rejection or stable renal function. Cytocentrifuged aliquots of urinary sediment were incubated with monoclonal antibodies to ICAM-1 in an avidin- biotin-peroxidase technique. To corroborate our findings, biopsy specimens were obtained for conventional and immunohistology one hour following vascular anastomosis and during rejection episodes. The proportion of renal tubular cells that expressed ICAM-1 was low in patients with acute tubular necrosis (23.8 ± 3.6%) and high in patients with rejection (53.1 ± 4.4% [SEM]) (P< .001). In 11 patients who recovered from rejection, the proportion of ICAM-1-positive renal tubular cells decreased from 55.9 ± 5.6% to 25.5 ± 4.3% (P< .05). In two patients who initially had acute tubular necrosis and then rejected their transplants, the expression of ICAM-1 on renal tubular cells tended to increase (from 27.5 ± 2.5% to 60.0 ± 20.0%, P = .12). In eight patients with acute tubular necrosis who never rejected their transplants, ICAM-1 expression remained low (23.1 ± 3.8%). Immunocytology correlated well with immunohistology and the clinical diagnosis. Our findings suggest that urine immunocytology may be useful in monitoring adhesion molecule expression by renal tubular cells.