Urine cytology and the diagnosis of renal allograft rejection: II. Studies using immunostaining

BACKGROUND: Urine immunocytology may provide a noninvasive method of investigating the antigens expressed by renal tubular cells. In previous investigations of patients with acute renal allograft rejection (AR), we showed that the adhesion molecule ICAM-1 is expressed by voided tubular cells. The up-regulation of ICAM-1, in turn, may be due to high circulating levels of interferon-gamma and/or TNF-α. We investigated the regulation of receptors for these cytokines and found a correlation between their expression and clinical events. STUDY DESIGN: For 10 patients who received transplants consecutively, freshly voided aliquots of urine were obtained on each hospital day and on each outpatient visit for a mean of 52.8 ±26.2 (SD) days. After cytocentrifugation, the samples were prepared by the avidin - biotin - immunoperoxidase technique in order to detect the presence or absence of ICAM-1, interferongamma receptor and TNF-α receptor (p 80) on the tubular cells. RESULTS: In nonrejecting patients, the tubular cells expressed the interferon-gamma receptor but not ICAM-1 or the TNF-α receptor. In patients with AR, the pattern was different. The tubular cells expressed ICAM-1 and the TNF-α receptor but not the interferon-gamma receptor. CONCLUSION: Urine immunocytochemistry may be useful to demonstrate the expression of cytokine receptors by renal epithelia.