Acute tubular necrosis

Background & objectives: In spite of potent immunosuppression, acute rejection continues to be the single largest cause of graft dysfunction after renal transplantation. Renal allograft biopsy, though invasive, continues to be the reference standard, though certain clinical and biochemical parameters are helpful in assessment of these patients. Acute renal allograft rejection is mediated by T lymphocytes, which express increased number of interIeukin-2 receptors (IL-2R). The soluble component of IL-2R in serum and urine may be useful in detecting early graft rejection. This study assesses the possibility of using serum and urinary IL-2R estimation in early prediction and diagnosis of acute renal allograft rejection.

Methods: Sequential estimation of serum and urinary IL-2R levels along with serum creatinine values were assessed in 23 live related renal allograft recipients. The age of renal allograft recipients was 35±8.3 yr, with male : female ratio of 22 : 1. Samples were collected pre-transplant (day O) and posttransplant upto 30 days and the patients were followed for 6 months after transplantation. Eight recipients experienced graft dysfunction and graft biopsies were evaluated.

Results: Serum and urinary IL-2R patterns along with serum creatinine levels were correlated with the occurrence of graft rejection on histology. Eight recipients experienced acute graft rejection after transplantation andTS had stable graft function. Serum IL-2R levels at various periods after transplantation were found to be significantly (P

Interpretation & conclusion: Sequential scrum and urinary 1L-2R assay may serve as a predicter for early graft dysfunction. Study with larger sample size and for longer duration is required to further validate the results.

Key words Interleukin-2 receptors - renal allograft rejection - T cell dysfunction - transplantation

Renal transplantation offers a definitive therapeutic modality for patients with end stage renal disease; however, 50 to 70 per cent of these patients suffer graft dysfunction after transplantation1. Despite potent immunosuppression, acute rejection continues to be the single largest cause of graft dysfunction in majority of patients. Cyclosporine toxicity, acute tubular necrosis (ATN) and infections may also contribute to the causation of graft dysfunction in some of these patients'. Apart from clinical indicators of the graft dysfunction such as increased body weight, decreased urine output, graft tenderness, raised serum creatinine and diethylene triamine penta acetic acid (DTPA) scan, the renal allograft biopsy continues to be the reference standard. Being invasive, the procedure is associated with potential risk. Fine needle aspirates have a lower risk, but being of limited usefulness, have not been widely applied.

Acute renal allograft rejection is mediated by T lymphocytes. T cells expressing cell surface interleukin-2 receptors (IL-2R) were found in the kidneys of renal allograft recipients2. On antigenic challenge, T cells in the graft express increased number of IL-2R. The component of the receptor released in soluble form as a consequence of activation is termed as soluble IL-2R (sIL-2R)3.4. The soluble IL-2R retains immuno-reactivity and ability to bind with IL-2, but it is about 55kD smaller than the membrane bound form5. The IL-2R is of considerable diagnostic and therapeutic interest in clinical transplantation. Monoclonal antibodies to IL2R inhibit T cell proliferation6 and prevent rejection of renal allografts7. The immunosuppressive potential of cyclosporine is critically related to its capacity to impair the production of IL-2. Initial clinical studies indicate that the soluble form of IL-2R is released in the serum and urine of renal allograft recipients experiencing acute rejection8.9, which can be measured directly by utilizing antibody against IL-2R10.

The development of a reliable, non-invasive and economical diagnostic test for graft rejection has so far been an elusive goal. The present study was undertaken to assess the possibility of using serum and urinary IL2R estimation in early prediction and diagnosis of acute renal allograft rejection.

Material & Methods

The study was performed on 40 consecutive live related renal allograft recipients during January - june 1999 at Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, a tertiary care hospital in north India. Post-transplant, all patients received triple drug immunosuppression consisting of prednisolone, azathiprorine and cyclosporine. Sequential serum (5 ml) and urinary ( 10 ml) samples were collected pretransplant and on post-transplant days 1,5, 10 and 30 in 23 patients; in the remaining 17 patients, sequential samples could not be collected hence excluded from the study. Serum and urinary samples were alliquoted and snap frozen at -40° C for estimation of soluble human IL-2R using enzyme immunoassay kit (Immunotech, France). The results were expressed in pM; normal reference range of serum IL-2R was 70±45pM (Immunotech, France).

all renal allograft recipients were followed for a period of 6 months after transplantation. Episode(s) of graft dysfunction, if any, were recorded; 8 of 23 experienced graft dysfunction during this period and graft biopsies were received for evaluation in all of them. Serum and urinary IL-2R patterns were correlated with the occurrence of graft rejection on histology (TableII). Serial serum creatinine estimation by alkaline picrate method11 using Jaffe's principle, was also performed up to 6 months post-transplant in all cases.

The study protocol was approved by the ethics committee of the institute. Data were analyzed using student's t-test for significance and Kaplan Meier survival curve using log rank test.

Results & Discussion

The age of renal allograft recipients ranged from 18 to 48 yr, (35±8.3, mean±SD yr), 22 of them were males and one was female. Eight renal allograft recipients experienced acute graft dysfunction within 3 to 16 days after transplantation whereas 15 had stable graft function with no evidence of acute rejection, infection or cyclosporine toxicity during 6 months posttransplantation. Histological evaluation of renal allograft biopsies obtained from 8 patients experiencing acute graft dysfunction revealed acute rejection (5 had acute cellular rejection and 3 had acute vascular rejection).

The patients experiencing acute renal allograft rejection showed higher concentration of serum IL2R at various periods after transplantation as compared to the non-rejection group and the rise was statistically significant (P

Survival curves were constructed with random pre-rejection IL-2R levels (cut-off value of > or = 150 pM of serum IL-2R was taken as high value). There was more chance for the graft rejection with serum IL2R level of > or = 150 pM during pre-rejection period (Figure).

Serum creatinine estimations performed at various periods after transplantation in the patients revealed that immediate pre-transplant (day O) serum creatinine levels in those enjoying stable graft function were 1.6 to 6.6 mg/dl (mean±SD = 4.89±1.96) whereas, those experiencing acute graft rejection after transplantation had creatinine levels of 5.2 to 9.2 mg/dl (mean±SD=7.1 5±1.40) which were significantly higher (P

Post transplant changes in serum and urinary IL2R in patients experiencing graft rejection have earlier been reported by Colvin8,12, however, urinary IL-2R levels were much variable. The rise in serum IL-2R is not specific to transplant rejection as raised serum IL-2R levels may be encountered in other conditions associated with T cell activation such as early stages of HIV, seropositivity13, IL-2 therapy14, posttransplant viral infections'5,16 and autoimmune diseases17. In our study none of the patients had any other cause of graft dysfunction during the first 6 months such as infections or cyclosporine toxicity and none of them received IL-2R therapy for graft rejection. Serum levels of IL-2R may be elevated due to poor clearance of 1L-2R by the kidney graft18. Further studies need to be done to study this aspect.

The present observations indicate that serum IL-2R may be a diagnostic and prognostic indicator in patients experiencing acute renal allograft rejection, however, the findings need further validation by studying large number of patients for a longer period before making any recommendations.

References

1. Colvin RB. Renal Transplant Pathology. In: Jennettce JC, Olson JL, Schwartz ML, Suva FG, editors. Heplinstall's pathology of kidney disease, vth ed. Philadelphia: LippincoltRaven; 1998 p. 1409-1540.

2. Hancock WW, Gee D, Dc Moerloose P, Rickles FR, Bwan VA, Atkins RC. Immunohistological analysis of serial biopsies taken during human renal allograft rejection: changing profile of infiltrating cells and activation of the coagulation system. Transplantation 1985; 39 : 430-8.

3. Rubin LA, Kurman CC, Fritz ME, Biddison WE, Boulin B, Yarchoan R, et al. Soluble interleukin 2 receptors are released from activated human lymphoid cells in vitro. Jlmmunol 1985; 735:3172-7.

4. Wagner DK, York-Jolley J, Malek TR, Derzofsky JA, Nelson DL. Antigen specific murinc T cell clones produce soluble interleukin 2 receptor on stimulation with specific antigens. J lmmunol 1986; 137:592-6.

5. Rubin LA, Jay G, Nelson DL. The released interleukin 2 receptor binds interleukin 2 efficiently. Jlmmunol 1986; 737: 3841-4.

6. Deeper JM, Leonard WJ, Robb RJ, Waldmann TA, Greene WC. Blockade of the interleukin 2 receptor by anti-Tac antibody: inhibition of human lymphocyte activation. J lmmunol 1983; 131 : 690-6.

7. Soulillou JP, Peyronett P, Le Maufl'B, Hourmant M, Olive D, Mawas C, et al. Prevention of rejection of kidney transplants by monoclonal antibody directed against interleukin 2. Lancet 1987; J: 1339-42.

8. Colvin RB, Fuller TC, MacKecn L, Rung PC, Ip SH, Cosimi AB. Plasma interleukin 2 receptor levels in renal allograft recipients. Clin lmmunol Immunopathol 1987; 43 : 273-6.

9. Cornaby A, Simpson M, Vann Rice R, Dcmpsey R. Madras P. Jenkins R, et al. Interleukin 2 levels and urine cytology distinguish between cyclosporine toxicity and rejection in renal and liver allograft recipients. Transplant 1'roc 1988; 20 (Suppl 3) : 82730.

10. Montagino G, Taranlion ?, Grignani S, Braga M, Ponlicelli C. Soluble interleukin-2 receptor (sIL-2R) levels in renal transplantation: comparison between clinical and laboratory analysis. Clin Transplant 1995; 9 : 25-30.

11. Varley H, Gomcnlock All, McMurray JR, McLauchlan DM. Creatine, urate and urea. In : Gomenlock AM, McMurray JR. McLauchlan DM, editors. Varley's practical clinical biochemistry, 6th ed. London : CRC Press; 1988 p. 350-1.

12. Colvin RB, Prcffer FI, FullerTC, Brown MC, Ip SI I, Kung PC, et al. A critical analysis of serum and urine intcrleukin-2 receptor assays in renal allograft recipients. Transplantation 1989; 48 : 800-4.

13. Sethi KK, Naher H. Elevated titers of cell-free interleukin 2 receptor in serum and cerebrospinal fluid specimens of patients with acquired immunodeficiency syndrome. Immunol Lett 1986; 13: 179-84.

14. Lotze MT, Güster MC, Sharrow SO, Rubin LA, Nelson DL, Rosenberg SA. In-vivo administration of purifieel human interleukin 2 to patients with cancer: development of interleukin 2 receptor positive cells and circulating soluble interleukin 2 receptors following interleukin-2 administration. Cancer Res 1987,47:2188-95.

15. Stole V, Krause JR. Interleukin-2 receptor levels are increased in blood of heart transplant patients during infection. Diagn Clin Immunol mi; 5: 171-4.

16. Tomkinson BE, Wagner DK, Nelson DE, Sullivan JL. Activated lymphocytes during acute Epstein-Barr virus infection. J Immunol 1987; 139: 3802-7.

17. Manoussakis MN, Papadopoulos GK, Drosos AA. Moutsopoulos HM. Soluble interleukin 2 receptor molecules in the scrum of patients with autoimmune diseases. Clin Imnnmol lmmunopathol 1989; 50 : 321-32.

18. Chen US, Wu MS, Chen WY, Lee SII, Yang CS. Scrum soluble interleukin-2 receptor in patients with end-stage renal disease on hemodialysis. Dialysis Transplant 1995; 24 : 459-65.

R.K. Gupta, Manoj Jain & R.K. Sharma*

Departments of Pathology & * Nephrology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India

Received june 9, 2003

Reprint requests : Dr R.K. Gupta, Professor and Head, Department of Pathology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow 226014, India

e-mail : rkgupta@sgpgi.ac.in

Copyright Indian Council of Medical Research Jan 2004
Provided by ProQuest Information and Learning Company. All rights Reserved