Do renal allograft function and histology at 6 months posttransplant predict graft function at 2 years?

Immune status assay (ISA): a noninvasive procedure for studying allograft rejection

BACKGROUND

There is a need for a simple, sensitive, noninvasive technique for monitoring graft function. We report here on a simple assay called immune status assay (ISA) that determines the status of the graft by simply examining the activation status of blood T cells.

METHODS

Graft-derived fibroblasts were used as a source of alloantigens and the recipient blood as a source of allograft-specific peripheral blood lymphocytes (PBL). PBL were added to wells containing donor or third-party graft-derived fibroblasts in the presence or absence of interleukin-2 (IL-2). On day 4 [(3)H]thymidine incorporation was quantified after the cells were incubated for 3 days at 37 degrees C, in a 5% CO(2) water-jacketed incubator. The results were analyzed using the following equation: %IL2 - /IL2+ = ((mean[(3)H]thymidine uptake in the absence of IL - 2) / (mean [(3)H]thymidine uptake in the presence of IL - 2)) x 100.

RESULTS

The ISA score (%IL-2 - /IL-2+) correlated strongly with the outcome of the graft, as it had a sensitivity of 82% for detecting rejections (14/17), and a specificity of 81% (30/37) for detecting non-rejections. Notably, the ISA detected immune T cell activation in the blood of graft rejecting subjects, which were not detected by currently used techniques such as mixed lymphocytes reaction.

CONCLUSION

The ISA is a straightforward procedure that detects allograft rejection with high specificity and sensitivity.

Molecular and structural consequences of early renal allograft injury

BACKGROUND

Chronic allograft nephropathy is an important cause of graft failure. Many donor and recipient factors contribute to its development. Prospective analysis of these factors has been hindered by the lack of sensitive and specific indicators of renal injury. As a consequence protocol biopsies have been increasingly used in the assessment of renal allograft injury. We performed protocol renal allograft biopsies to prospectively examine the role of important determinants and mediators of chronic allograft nephropathy.

METHODS

A total of 51 consecutive cadaveric renal transplant recipients entered a randomized prospective study of tacrolimus (Tac) versus cyclosporine (CsA) microemulsion based immunosuppression. Study patients underwent protocol renal allograft biopsies at the time of engraftment and at 3, 6 and 12 months post-transplantation. Biopsies were analyzed by quantitative polymerase chain reaction (PCR) for mRNA for transforming growth factor-beta (TGF-beta), thrombospondin, and fibronectin. Measurements of renal structural injury were estimated by quantitative assessment of interstitial fibrosis and glomerulosclerosis. Changes in profibrotic growth factors and renal structural injury were related to donor and recipient determinants by stepwise regression analysis.

RESULTS

Longitudinal assessment of renal injury demonstrated an early and progressive increase in mRNA for TGF-beta, thrombospondin (TSP) and fibronectin (FBN): TGF-beta baseline, 1.9 +/- 0.2 log copies; TGF-beta 6 months, 2.5 +/- 0.2 log copies, P < 0.05 6 months vs. baseline; TSP baseline, 1.9 +/- 0.2 log copies; TSP 6 months, 2.4 +/- 0.2 log copies, P < 0.05 6 months vs. baseline; FBN baseline, 2.0 +/- 0.2 log copies; FBN 12 months, 2.3 +/- 0.2 log copies, P < 0.05 12 months vs. baseline. This increase in profibrotic growth factors within the allograft was associated with a significant increase in interstitial fibrosis (Vvi) on renal biopsies: Vvi baseline, 13 +/- 1%; Vvi 3 months, 18 +/- 1%; Vvi 6 months, 28 +/- 2%; Vvi 12 months, 34 +/- 2%; P < 0.05 3, 6, and 12 months vs. baseline. Histological analysis demonstrated chronic allograft nephropathy in 4% biopsies at 3 months, 12% at 6 months and in 49% at 12 months. These changes in renal structure were not associated with any change in creatinine clearance (CCr): CCr 3 months, 56 +/- 2 mL/min, CCr 24 months, 56 +/- 2 mL/min; P=NS. Stepwise regression analysis of key donor and recipient determinants of chronic renal injury identified calcineurin inhibitors and acute rejection episodes as important factors involved in the development of chronic renal injury. In particular, the use of cyclosporine compared to tacrolimus was associated with a tenfold increase in TGF-beta mRNA (TGF-beta mRNA at 6 months, CsA vs. Tac, 3 +/- 0.3 vs. 2 +/- 0.3 log copies, P < 0.05), interstitial fibrosis (Vvi at 6 months, CsA vs. Tac, 33 +/- 4% vs. 24 +/- 2%, P < 0.05). Changes in growth factors and renal structure predicted impaired renal function (CCr at 12 months, CsA vs. Tac, 53 +/- 4 mL/min vs. 62 +/- 2 mL/min, P < 0.05). Similarly, acute rejection episodes were associated with an accelerated development of interstitial fibrosis (Vvi at 6 months, acute rejection vs. no rejection, 34 +/- 3% vs. 25 +/- 2%; P < 0.05), but not with changes in TGF-beta, thrombospondin or fibronectin expression.

CONCLUSION

Our results suggest that structural injury develops early in the natural history of the renal allograft and is mediated, in part, by the early up-regulation of profibrotic growth factors. We have determined that calcineurin inhibitors, in particular cyclosporine, and acute rejection episodes are key factors in the development of renal structural injury.

Renal allograft rejection with normal renal function in simultaneous kidney/pancreas recipients: does dissynchronous rejection really exist?

BACKGROUND

Between July 1, 1994 and December 1, 1998, 147 simultaneous kidney/pancreas transplantations were performed at our center. Of 95 patients who experienced at least one acute renal allograft rejection episode after transplantation, 7 (7.4%) developed rejection in the presence of stable and normal or near-normal renal function.

METHODS

The indication for renal allograft biopsy was a rising serum lipase, i.e., suspected pancreatic rejection. All seven patients were treated with steroids and augmentation of the tacrolimus dose, with a fall in the serum lipase and no change in the serum creatinine.

RESULTS

The serum creatinine levels just before, at the time of, 1 week after the biopsy, and at most recent follow-up were 1.4+/-0.4, 1.3+/-0.3, 1.2+/-0.2, and 1.2+/-0.2 mg/dl. The serum lipase levels just before, at the time of, 1 week after the biopsy, and at most recent follow-up were 1022+/-1157 mg/dl, 874+/-996 mg/dl, 243+/-260 mg/dl, and 94+/-75 mg/dl. The tacrolimus dosages and levels at the time of the biopsy and 1 week later were 14.9+/-5.0 mg/day and 15.0+/-4.0 ng/ml, and 16.4+/-6.3 mg/day and 15.1+/-6.8 ng/ml.

CONCLUSIONS

These findings suggest that, in patients undergoing simultaneous kidney/pancreas transplantation, the entity of dissynchronous pancreatic allograft rejection without renal allograft rejection may not really exist. These data also make an additional fundamental point that acute rejection may occur in patients with normal and stable renal function.

Computerized histomorphometric assessment of protocol renal transplant biopsy specimens for surrogate markers of chronic rejection

BACKGROUND

Chronic transplant rejection has emerged as the commonest cause of long-term renal allograft failure, and early identification of those grafts at risk could allow the targeting of specific therapies aimed at delaying this process. This study explores the usefulness of quantitative immunohistochemistry in defining biopsy-based surrogate markers of allograft damage.

METHODS

A consecutive series of 52 renal transplant recipients immunosuppressed with cyclosporine were studied. Needle core transplant biopsies were performed at 1, 3, and 6 months postoperatively. Immunostaining for collagen III, and smooth muscle actin, tenascin, and infiltrating leukocytes was performed using an indirect immunoperoxidase technique. The interstitial area stained (%) was measured using a semiautomatic image analysis system. The results were related to glomerular filtration rates (GFR) measured at 6, 12, and 24 months after transplantation using rank correlation coefficients.

RESULTS

The area fraction of immunostained collagen III correlated with 6-month GFR (r=-0.42, P=0.005) and was predictive of 12-month GFR (r=-0.32, P=0.03). An area fraction of immunostained collagen III of >40% at 6 months was associated with a significantly lower GFR at 24 months, compared with a percentage area of < or =40% (31+/-4 versus 45+/-4 ml/min/1.73 m2, P=0.01). Furthermore, a collagen III of >40% at 6 months identified patients who were at risk of progressive deterioration in graft function.

CONCLUSIONS

Grafts with poorer long-term function can be predicted using 6-month protocol biopsy specimens immunostained for collagen III. This should prove to be a useful ad interim surrogate marker of allograft damage in studies addressing the effects of new immunosuppressive agents on the development of chronic rejection.