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

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-alpha. We investigated the regulation of receptors for these cytokines and found a correlation between their expression and clinical events.

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, interferon-gamma receptor and TNF-alpha receptor (p 80) on the tubular cells.

In nonrejecting patients, the tubular cells expressed the interferon-gamma receptor but not ICAM-1 or the TNF-alpha receptor. In patients with AR, the pattern was different. The tubular cells expressed ICAM-1 and the TNF-alpha receptor but not the interferon-gamma receptor.

Urine immunocytochemistry may be useful to demonstrate the expression of cytokine receptors by renal epithelia.