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-alpha. 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, interferon-gamma receptor and TNF-alpha 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-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. CONCLUSION: Urine immunocytochemistry may be useful to demonstrate the expression of cytokine receptors by renal epithelia.

Urine cytology and the diagnosis of renal allograft rejection. I. Studies using conventional staining.

OBJECTIVE: To determine the reproducibility and validity of urine cytology for the diagnosis of acute renal allograft rejection (AR). STUDY DESIGN: We conducted a blind, prospective study of 10 renal allograft recipients. Freshly voided aliquots of urine were obtained on each hospital day and at each outpatient visit for a mean of 52.8 +/- 26.2 (SD) days following transplantation. The samples were prepared by cytocentrifugation and then stained by a modified Papanicolaou method. To determine interobserver reproducibility, the differential cell counts of two blinded cytopathologists were compared. A cytodiagnosis of AR was made when the urine sample contained < 55% neutrophils and > 20% lymphocytes. To determine the validity of the cytology, the result was compared to the histologic and clinical diagnoses. Biopsies were obtained one hour following vascular anastomosis and at the time of graft dysfunction and were scored by two blinded pathologists according to the Banff classification. The clinical diagnosis was determined by a retrospective review conducted by four blinded clinicians. RESULTS: The interoperator reading of urine cytology was more reproducible than histology, with kappa values of 0.40 +/- 0.15 (SE) and 0.21 +/- 0.10 (SE), respectively. Urine cytology was accurate for the diagnosis of AR, with a sensitivity of 80% and a specificity of 96% as compared to the clinical and histologic findings. CONCLUSION: Our observations support the claim that urine cytology is useful for diagnosing AR.

Urine cytology: an underused method to diagnose acute renal allograft rejection.

In children, the early detection and accurate diagnosis of acute renal allograft rejection (AR) may be difficult. A delay in the diagnosis and treatment of AR might engender a poor outcome. Core needle biopsy is diagnostic but invasive. However, only a few less-invasive means to diagnose AR are sufficiently accurate to warrant their routine use. One such method is urine cytology. Investigators have demonstrated in more than 800 patients that urine cytology is simple and reliable for diagnosing graft failure. These observations may be important for children, for whom a non-invasive, accurate, and easily repeated indicator of AR may be particularly useful. While not a substitute for transplant biopsy, urine cytology may reduce diagnostic uncertainty and indicate the need for core needle sampling in a timely manner.

Improved renal allograft survival in children treated with FK 506 (tacrolimus) rescue therapy.

FK 506 has been reported to be effective in reversing acute renal allograft rejection that is resistant to steroids and to OKT3. The contribution of FK 506 "rescue" therapy to long-term graft survival has not been determined. We report 23 children transplanted between January 1993 and December 1994, 10 of whom received FK 506 "rescue" therapy. Acute rejection was reversed in 8 of 10, with 7 of the remaining grafts still functioning after a mean follow-up of 10.9 +/- 7.8 (SD) months (range 1-26 months). The actuarial 1-year graft survival rate was 86% compared with 66% for historical controls (P < 0.05). We conclude that FK 506 may provide long-term benefits to children facing allograft loss due to acute rejection.

Renal allograft rejection in children and young adults: the Banff classification.

In the Banff classification, arteritis and tubulitis are regarded as the principal histological lesions indicating acute renal allograft rejection. To test this claim, we examined 51 biopsies obtained from 21 children and young adults with transplant rejection. Two reviewers, blind to the clinical course, graded the biopsies according to the Banff scheme. In patients without significant tubulitis (borderline changes), rejection tended to be reversed easily (88%), often with methylprednisolone pulse (52%). In patients with arteritis or significant tubulitis (Banff I-III), rejection was reversed in only 23% (P < 0.001), in 9% with steroids, and in 14% with OKT3. Salvage of the graft was achieved in 26 of 35 (74%) with a score < 5 but in only 1 of 12 (8%) with a score > or = 5 (P < 0.001). All 6 patients with vasculitis lost their grafts despite methylprednisolone pulse and OKT3. We conclude that the Banff classification predicts accurately the outcome of renal allograft rejection in children and may aid in choosing appropriate therapy.

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.

Sequential occurrence of IgA nephropathy and Henoch-Schönlein purpura: support for common pathogenesis.

We report a patient who developed Henoch-Schönlein purpura (HSP) 13 years after he presented with IgA nephropathy (IgAN). In both HSP and IgAN renal biopsy most commonly reveals focal proliferative glomerulonephritis on light microscopy and immunofluorescence displays mesangial IgA deposits. In addition, patients with HSP or IgAN have elevated serum IgA levels, circulating IgA immune complexes, IgA-bearing lymphocytes, immunoglobulin-producing cells, and binding of IgG to glomerular components of similar molecular weight. The occurrence of both diseases in the same patient or the same families and the presence of immune abnormalities compatible with HSP or IgAN in relatives of patients with these diseases suggest a common pathogenesis.

The fractional excretion of urea: a new diagnostic test for acute renal allograft rejection.

Fractional excretion of sodium (FENa) has been used in the diagnosis of acute renal allograft failure on the assumption that poor allograft perfusion should result in a low FENa. However, many patients receive medications which affect the active transport of Na+ and thus FENa. In contrast, the fractional excretion of urea (FEurea) is mostly dependent on passive forces and is therefore less influenced by drug therapy. To test the hypothesis that FEurea might be more useful than FENa in evaluating graft failure, we compared FEurea with FENa during 79 episodes of acute renal allograft dysfunction due to acute rejection (AR), cyclosporine nephrotoxicity (CsA-Nx), viral infection, or bacterial infection in 32 children and young adults with renal transplants. There was no significant difference between groups in FENa. However, FEurea was significantly lower (P < 0.05) in patients with CsA-Nx (32.6 +/- 1.9%) and viral infection (32.9 +/- 3.2%) than those with AR (45.1 +/- 1.7%) or bacterial infection (38.9 +/- 2.5%). FEurea was < 35% in 20 of 28 (71.4%) episodes of CsA-Nx and 8 of 11 (72.2%) of viral infection, but only 5 of 36 (13.9%) of AR (P < 0.05). FEurea was also measured during stable graft function, 7-14 days prior to allograft dysfunction. CsA-Nx was associated with a 30.5 +/- 8.3% decrease in FEurea. FEurea did not change in patients with AR. Based on these findings, we present an algorithm to aid in the differential diagnosis of acute renal allograft failure.

Case report 668. Carbonic anhydrase II deficiency syndrome (osteopetrosis associated with renal tubular acidosis and cerebral calcification).

A 4-month-old infant with bronchiolitis was found to have hyperdense bones on chest roentgenograms. The diagnosis of osteopetrosis was demonstrated by generalized increased radiological bone density and by a bone biopsy showing persistence of calcified cartilage. The infant also had a mixed proximal and distal renal tubular acidosis requiring as much as 12 mEq/kg per day of sodium bicarbonate. Measurement of his erythrocyte carbonic anhydrase activity revealed a deficiency of CA II. His parents showed values of CA activity that were intermediate between controls and the proband. Thus, this is a patient with the CA II deficiency syndrome; he is the youngest reported case without any family history of osteopetrosis to be diagnosed initially on the basis of his radiographic features.