Serum C-reactive protein. A useful and economical marker of immune activation in renal transplantation

Biomarkers of the Complement System Activation (C3a, C5a, sC5b-9) in Serum of Patients before and after Liver Transplantation

The liver has a huge impact on the functioning of our body and the preservation of homeostasis. It is exposed to many serious diseases, which may lead to the chronic failure of this organ, which is becoming a global health problem today. Currently, the final form of treatment in patients with end-stage (acute and chronic) organ failure is transplantation. The proper function of transplanted organs depends on many cellular processes and immune and individual factors. An enormous role in the process of acceptance or rejection of a transplanted organ is attributed to, among others, the activation of the complement system. The aim of this study was the evaluation of the concentration of selected biomarkers' complement system activation (C3a, C5a, and sC5b-9 (terminal complement complex)) in the serum of patients before and after liver transplantation (24 h, two weeks). The study was conducted on a group of 100 patients undergoing liver transplantation. There were no complications during surgery and no transplant rejection in any of the patients. All patients were discharged home 2-3 weeks after the surgery. The levels of all analyzed components of the complement system were measured using the ELISA method. Additionally, the correlations of the basic laboratory parameters-C-reactive protein (CRP), hemoglobin (Hb), total bilirubin, alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGTP), and albumin-with the parameters of the complement system (C3a, C5a, and sC5b-9) were determined. In our study, changes in the concentrations of all examined complement system components before and after liver transplantation were observed, with the lowest values before liver transplantation and the highest concentration two weeks after. The direct increase in components of the complement system (C3a, C5a, and sC5b-9) 24 h after transplantation likely affects liver damage after ischemia-reperfusion injury (IRI), while their increase two weeks after transplantation may contribute to transplant tolerance. Increasingly, attention is being paid to the role of C3a and CRP as biomarkers of damage and failure of various organs. From the point of view of liver transplantation, the most interesting correlation in our own research was found exactly between CRP and C3a, 24 h after the transplantation. This study shows that changes in complement activation biomarkers and the correlation with CRP in blood could be a prognostic signature of liver allograft survival or rejection.

The 82-plex plasma protein signature that predicts increasing inflammation

The objective of the study was to define the specific plasma protein signature that predicts the increase of the inflammation marker C-reactive protein from index day to next-day using proteome analysis and novel bioinformatics tools. We performed a prospective study of 91 incident kidney transplant recipients and quantified 359 plasma proteins simultaneously using nano-Liquid-Chromatography-Tandem Mass-Spectrometry in individual samples and plasma C-reactive protein on the index day and the next day. Next-day C-reactive protein increased in 59 patients whereas it decreased in 32 patients. The prediction model selected and validated 82 plasma proteins which determined increased next-day C-reactive protein (area under receiver-operator-characteristics curve, 0.772; 95% confidence interval, 0.669 to 0.876; P < 0.0001). Multivariable logistic regression showed that 82-plex protein signature (P < 0.001) was associated with observed increased next-day C-reactive protein. The 82-plex protein signature outperformed routine clinical procedures. The category-free net reclassification index improved with 82-plex plasma protein signature (total net reclassification index, 88.3%). Using the 82-plex plasma protein signature increased net reclassification index with a clinical meaningful 10% increase of risk mainly by the improvement of reclassification of subjects in the event group. An 82-plex plasma protein signature predicts an increase of the inflammatory marker C-reactive protein.

Utility of procalcitonin as an early diagnostic marker of bacteremia in patients with acute fever

PURPOSE

Procalcitonin (PCT) is a current, frequently used marker for severe bacterial infection. The aim of this study was to assess the ability of PCT levels to differentiate bacteremic from nonbacteremic patients with fever. We assessed whether PCT level could be used to accurately rule out a diagnosis of bacteremia.

MATERIALS AND METHODS

Serum samples and blood culture were obtained from patients with fever between August 2008 and April 2009. PCT was analyzed using a VIDAS® B.R.A.H.M.S PCT assay. We reviewed the final diagnosis and patient histories, including clinical presentation and antibiotic treatment.

RESULTS

A total of 300 patients with fevers were enrolled in this study: 58 with bacteremia (positive blood culture) (group I); 137 with local infection (group II); 90 with other diseases (group III); and 15 with fevers of unknown origin (group IV). PCT levels were significantly higher in patients with bacteremia than in those with non-bacteremia (11.9 ± 25.1 and 2.5 ± 14.7 ng/mL, respectively, p < 0.001). The sensitivity and specificity were 74.2% and 70.1%, respectively, at a cut-off value of 0.5 ng/mL. A serum PCT level of < 0.4 ng/mL accurately rules out diagnosis of bacteremia.

CONCLUSION

In febrile patients, elevated PCT may help predict bacteremia; furthermore, low PCT levels were helpful for ruling out bacteremia as a diagnosis. Therefore, PCT assessment could help physicians limit the number of prescriptions for antibiotics.

The potential role of C-reactive protein in distinguishing cytomegalovirus from tuberculosis and bacterial infections in renal transplant recipients

INTRODUCTION

The delay in the diagnosis of infections can be deleterious in renal transplant recipients. Thus, laboratory tests leading to an earlier diagnosis are very useful for these patients.

PURPOSE

To assess the behavior of C-reactive protein (CRP) in renal transplant recipients with a diagnosis of cytomegalovirus (CMV) infection, tuberculosis (TB) and bacterial infection (BI).

METHODS

A retrospective analysis of 129 patients admitted at our hospital, from 2006 to 2008 because of CMV, TB or BI, was carried out. Appropriate statistical analysis was done and values were expressed as medians, range.

RESULTS

When CRP levels were compared among the groups with CMV disease, TB or BI, the group with CMV disease presented lower levels of CRP (18.4 mg/L, 0.28-44 mg/L) than the TB and BI (p < 0.05) groups. The area under the receiver-operating characteristics curve, distinguishing CMV disease from TB/BI, was 0.96 (p < 0.0001), resulting in 100% sensitivity and 90.63% specificity to detect CMV disease when CRP < 44.5 mg/L. The subgroup analysis of CMV infection showed increasing levels of CRP (0.28, 16 and 29.5 mg/L) in the asymptomatic, symptomatic and invasive disease subgroups, respectively (p < 0.05).

CONCLUSION

The measurement of CRP levels may be a useful tool for differentiating CMV infection from the other types (bacterial or TB) of infection in kidney transplant recipients.

Acute renal allograft rejection is associated with increased levels of vascular endothelial growth factor in the urine

AIM

The purpose of this study was to assess whether measurement of urinary vascular endothelial growth factor (VEGF) could be adopted as a new non-invasive diagnostic tool for acute rejection following renal transplantation.

METHODS

Urinary concentration of VEGF was determined by an enzyme-linked immunosorbent assay technique in 215 renal allograft recipients and 80 healthy controls.

RESULTS

Subjects with acute rejection (n=67) excreted urinary VEGF at a significantly higher level (28.57+/-6.21, 95% CI: 16.18-40.97 pg/mumol creatinine) than those without acute rejection. This included subjects with stable renal function and no abnormal histological findings (n=119), acute tubular necrosis (n=15), chronic allograft nephropathy (n=14) and healthy controls (n=80). Using a urinary VEGF/creatinine ratio of 3.64 pg/micromol as the cut-off point, the sensitivity and specificity for diagnosing acute rejection were 85.1 and 74.8%, respectively (P<0.001). Patients with steroid-resistant acute rejection had significantly greater urinary VEGF concentration than patients with steroid-sensitive acute rejection (42.09+/-10.00 vs 9.74+/-2.63 pg/micromol creatinine, P<0.001). Patients with graft loss after acute rejection had significantly greater urinary VEGF concentration than patients with reversible acute rejection (106.66+/-38.60 vs 19.46+/-4.13 pg/micromol creatinine, P=0.001). Using a urinary VEGF/creatinine ratio of 22.48 pg/micromol as the cut-off point, the sensitivity and specificity of the prediction to graft loss after acute rejection were 85.7% and 78.3%, respectively (P=0.001).

CONCLUSION

This study demonstrates that the monitoring of urinary VEGF may be a useful non-invasive approach for the detection of acute rejection. Additionally, urinary VEGF levels were shown to predict the response to anti-rejection therapy and to predict a poor outcome after acute rejection.

Serum C-reactive protein surge in renal transplant recipients: link with allograft survival

The restoration of kidney function by transplantation improves the common finding of chronic inflammation in patients with end-stage renal disease (ESRD). The C-reactive protein (CRP) level is a reliable marker of inflammation in renal transplant recipients. We analyzed the predictive value of posttransplant CRP surges on renal allograft survival among 141 ESRD patients who underwent renal transplantation between May 1999 and September 2001 at our institution. Twenty-seven cadaveric and 114 living donors were also studied. The subjects' demographic, clinical, and laboratory data were recorded. The renal transplant recipients were divided into three groups defined by the type of serum CRP surge: a normal, intermittently high, or consistently high serum CRP concentration. Renal allograft survival rates were 90.0% among recipients with normal serum CRP concentrations, 72.6% among those with intermittently high concentrations, and 11.1% in those with consistently high concentrations. A Cox regression analysis of factors that affect allograft survival showed that acute rejection, advanced recipient age, and consistently high serum CRP concentrations were associated with a high risk of renal allograft loss. Intermittent elevations in the serum CRP level were not associated with an increased risk of allograft loss, according to the Cox regression model. We concluded that consistently high serum CRP concentrations in renal allograft recipients showed a high negative predictive value for renal allograft survival. In recipients who exhibited ongoing inflammatory process in the 5-year posttransplant period, additional efforts are necessary to manage inflammation and therefore prolong renal allograft survival.

Primary immunization of premature infants with gestational age <35 weeks: cardiorespiratory complications and C-reactive protein responses associated with administration of single and multiple separate vaccines simultaneously

OBJECTIVE

To determine the incidence of cardiorespiratory events and abnormal C-reactive protein (CRP) level associated with administration of a single vaccine or multiple separate vaccines simultaneously.

STUDY DESIGN

Prospective observational study on 239 preterm infants at > or =2 months of age in the neonatal intensive care unit (NICU). Each infant received either a single vaccine or multiple vaccines on one day. CRP levels and cardiorespiratory manifestations were monitored for 3 days following immunization.

RESULTS

Abnormal elevation of CRP level occurred in 85% of infants administered multiple vaccines and up to 70% of those given a single vaccine. Overall, 16% of infants had vaccine-associated cardiorespiratory events within 48 hours postimmunization. In logistic regression analysis, abnormal CRP values were associated with multiple vaccines (OR, 15.77; 95% CI 5.10-48.77) and severe intraventricular hemorrhage (IVH) (OR, 2.28; 95% CI 1.02-5.13). Cardiorespiratory events were associated marginally with receipt of multiple injections (OR, 3.62; 95% CI 0.99-13.25) and significantly with gastroesophageal reflux (GER) (OR, 4.76; 95% CI 1.22-18.52).

CONCLUSION

CRP level is expected to be elevated in the 48 hours following immunization. In a minority of infants immunized, cardiorespiratory events were associated with presumed need for intervention. Underlying medical conditions and possibly multiple injections are associated with cardiorespiratory events. Precautionary monitoring following immunizations is warranted.

A J-shaped association between high-sensitivity C-reactive protein and mortality in kidney transplant recipients

In kidney transplant recipients (KTR), C-reactive protein (CRP) has been shown to be associated with increased mortality, but data on this association within the high-sensitivity (hs) range of CRP (<5 mg/l) are lacking. We prospectively studied 710 prevalent and stable KTR over >6 years. We thawed frozen plasma and measured baseline hs-CRP using an ultrasensitive assay. Detailed clinical and demographic baseline characteristics were available for study. We stratified patients by quartile of hs-CRP within the hs range (<5 mg/l), and also included KTRs whose hs-CRP was above the hs range (>5-10 and >10 mg/l). We used multivariate proportional hazards models to test for independent associations. After careful multivariate adjustment, we found a J-shaped association between hs-CRP and mortality. Compared with KTR whose hs-CRP was in the second lowest quartile of hs-CRP (0.06-1.26 mg/l), patients in the lowest quartile (<0.06 mg/l) had more than twice their mortality risk (HR = 2.07; 95% CI: 1.05-4.07), as did patients whose hs-CRP was > or =2.44 mg/l (all HRs >2.27). No association was found between hs-CRP and death-censored allograft loss. In contrast to the general population, the association between hs-CRP and mortality in KTRs is not linear, but J-shaped, suggesting that KTRs with very low hs-CRP may also be at increased risk of death.

Clinical laboratory differentiation of infectious versus non-infectious systemic inflammatory response syndrome

OBJECTIVE

To evaluate the accuracy of C-reactive protein (CRP), procalcitonin (PCT), neopterin, and endotoxin in the differential diagnosis of sepsis and non-infectious systemic inflammatory response syndrome (SIRS).

METHODS

A Medline database and references from identified articles were used to perform a literature search relating to the differential diagnosis of sepsis versus non-infectious SIRS.

RESULTS

CRP, PCT, and neopterin are released both in sepsis and in non-infectious inflammatory disease. CRP and PCT are equally effective, although not perfect, in differentiating between sepsis and non-infectious SIRS. However, CRP and PCT have different kinetics and profiles. The kinetics of CRP is slower than that of PCT, and CRP levels may not further increase during more severe stages of sepsis. On the contrary, PCT rises in proportion to the severity of sepsis and reaches its highest levels in septic shock. PCT tends to be higher in nonsurvivor than in survivor. Therefore, PCT demonstrated a closer correlation with the severity of sepsis and outcome than CRP. Unlike CRP and PCT, neopterin is increased in viral infection as well as bacterial infection, and neopterin is also a useful indicator of sepsis. Endotoxemia was detected in no more than half of patients with Gram-negative bacteremia, and Gram-negative bacteremia was detected in half of patients with endotoxemia.

CONCLUSIONS

The diagnostic capacity of PCT is superior to that of CRP due to the close correlation between PCT levels and the severity of sepsis and outcome. Neopterin is very useful in the diagnosis of viral infection. The endotoxin assay in combination with CRP, PCT, or neopterin may help as a diagnostic marker for Gram-negative bacterial infection.

Post-transplant C-reactive protein monitoring can predict chronic allograft nephropathy

Chronic allograft nephropathy (CAN) is a major problem after renal transplantation and chronic inflammation can be one of its promoters. C-reactive protein (CRP) is an important marker of inflammation and atherosclerosis. We retrospectively analyzed the predictive role of serum CRP levels on the development of CAN and graft failure. One hundred and twenty-five renal transplant patients were randomly included into the study. Serum CRP levels were measured at pre-transplant period, first month after transplantation and at yearly intervals throughout follow-up. CAN was diagnosed in 40.8% of patients and 82.4% of them had graft failure in 60.9 +/- 36.7 months. There was no difference at pre-transplant CRP levels of patients with and without CAN, but the first month CRP levels were higher in those who experienced CAN. The initial 3-yr mean CRP levels were higher, but not statistically different between the patients with and without CAN. The simultaneously detected CRP levels when CAN were diagnosed was significantly higher in those with CAN. High post-transplant CRP levels at the first month and at the diagnosis of CAN significantly influenced the allograft failure according to the regression analysis. CRP monitoring gives important information about the risk for CAN and graft failure. Therefore, CRP levels should be included in the follow-up data after renal transplantation.

Serum C-reactive protein in pediatric kidney and liver transplant patients

The clinical manifestations of different complications after organ transplantation (Tx) are often vague, and simple laboratory tests for early diagnosis would be valuable. In this work we retrospectively analyzed our data on the daily measurements of serum C-reactive protein (CRP) in 132 children after 63 liver and 83 kidney Txs. A total of 3,886 CRP measurements were performed and 353 episodes of elevated CRP were recorded. One-third of these were regarded as a response to surgery. The CRP level normalized within 5-10 days post-operatively in patients who had a favorable outcome, but in patients with a poor outcome CRP tended to remain elevated. Half of the CRP elevations were associated with complications such as acute rejection, infection or thrombotic events. An elevated serum CRP level was found in 68% of the rejection episodes, in 88% of the bacterial infections, and in 73% of the viral infections. The most significant elevations were associated with bacterial infection. In nine of 11 vascular complications, an elevation of CRP was also recorded. Serum CRP responded to rejection therapy in 86% of the episodes. The initial CRP level did not predict steroid-resistant rejection. CRP seemed to be a more sensitive marker than fever or white blood cell (WBC) count in all complications. We conclude that the daily measurement of serum CRP is a simple and fairly sensitive, but non-specific, method for detecting rejection and infectious complications after pediatric liver and kidney Tx.

Do serum C-reactive protein measurements help to discriminate episodes of renal dysfunction in patients after renal transplantation?

INTRODUCTION

This study investigated whether serial daily measurements of serum C-reactive protein (sCRP) could help differentiate episodes of transplant dysfunction due to rejection, infection, cyclosporine A (CsA) nephrotoxicity, or acute tubular necrosis (ATN) in renal-allograft recipients.

MATERIALS AND METHODS

Morning serum was obtained daily from 134 patients during the first 30 days after renal transplantation. All episodes of graft dysfunction were recorded and differentiated with transplant biopsies. CRP concentrations were correlated with post-operative graft function and the various causes of graft dysfunction.

RESULTS

All patients showed an increase in sCRP in response to surgery, with a maximum on day 2 after transplantation. The sCRP concentration was significantly higher in patients with delayed graft function (mean 61.50 microg/ml) than in patients with primary graft function (mean 38.01 microg/ml) (p=0.001). Bacterial infections other than asymptomatic bacteriuria (mean sCRP 33.98 microg/ml), interstitial graft rejection (mean sCRP 16.43 microg/ml), and ATN (mean sCRP 30.50 microg/ml) were accompanied by significant increases in sCRP compared with uneventful courses. sCRP was unchanged in the presence of viral infections or CsA toxicity.

CONCLUSION

Serial sCRP measurements help to identify renal-transplant dysfunction of different origins. However, rejection, infection and ATN show similar patterns of sCRP increase. Thus, sCRP is unable to discriminate the causes of renal-graft dysfunction. Biopsy remains the gold standard for the differential diagnosis of renal-allograft dysfunction.

Soluble intercellular adhesion molecule-1 (sICAM-1) after kidney transplantation: the origin and role of urinary sICAM-1?

BACKGROUND

Intercellular adhesion molecule-1 (ICAM-1) binds to leukocyte adhesion receptors LFA-1 and MAC-1, and mediates leukocyte adhesion to target structures. During acute rejection there is increased expression of ICAM-1 in vascular and tubulointestial cells, and consequently accumulation of inflammatory leukocytes. Soluble ICAM-1 (sICAM-1) is released from ICAM-1 expressing cells and excreted into the surrounding fluid. Increased serum sICAM-1 levels are found in patients with acute rejections of various allografts, and high urinary levels in steroid resistant acute kidney allograft rejection.

METHODS

Urinary excretion of sICAM-1 was measured by EIA in 136 kidney allograft recipients during the first 1-6 post transplant weeks: 30 patients developed acute rejection, and 106 patients had stable graft function. The molecular weight, binding to hyaluronan, and the origin of urinary sICAM-1 were studied.

RESULTS

We show that urinary sICAM-1 circulates as a monomer with a molecular weight between 50 and 100 kD. It binds to immobilized, but not to circulating hyaluronan. About one week after transplantation the mean sICAM-1/creatinine ratio (306 ng/mmol) in transplanted patients was higher than in the healthy controls (167 ng/mmol, P<0.01), and remained basically unchanged during the follow-up in patients with stable graft function, whereas it increased in patients developing rejection, being about 2.5-fold above the initial level a few days before rejection (P<0.01). Urinary sICAM-1 did not correlate with the urinary albumin, whereas in patients developing rejection it correlated with urinary IL-2R (r=0.5146, P<0.001), a marker of lymphocyte activation. In the urinary sediment of rejecting patients ICAM-1 was demonstrated in the tubular epithelial cells, and in the macrophages.

CONCLUSIONS

Increased urinary excretion of sICAM-1 was demonstrated in kidney transplanted patients a few days before acute rejection. It seems to originate from activated macrophages and/or from the tubular epithelial cells. The fact that urinary sICAM-1 is not bound to hyaluronan or to leukocytes suggests that it is not able to compete with membrane-bound ICAM-1 for these bindings, but may do so for the binding of activated macrophages.

Pretransplant systemic inflammation and acute rejection after renal transplantation

BACKGROUND

There are presently no established pre-transplant tests that consistently identify patients who may be at increased risk for acute rejection episodes after renal transplantation. We studied whether pretransplant serum levels of C-reactive protein (CRP), a marker for the presence of systemic inflammation, would predict the occurrence of acute rejection episodes after renal transplantation.

METHODS

Pretransplant serum was tested for CRP level in 97 consecutive renal transplant recipients. Time to acute rejection after transplantation was stratified by CRP level and compared using the Kaplan-Meier method. In addition, Cox regression multivariate analysis was performed to assess whether any pretransplant covariates could independently predict the subsequent occurrence of acute rejection episodes.

RESULTS

Pretransplant mean CRP levels were higher in patients who subsequently had a rejection episode versus those who had no rejection (22.2+/-2.9 vs. 11.7+/-1.8 microg/ml, respectively, P=0.003). Patients less than the median CRP value had a significantly longer time to rejection compared to those with higher CRP levels (P=0.002). Similarly, patients within the lowest CRP quartile had longer times to rejection when compared with the highest quartile (P=0.006). Cox proportional hazards regression multivariate analysis identified CRP level as the only independent pretransplant risk factor for rejection identified (P=0.044).

CONCLUSIONS

Pretransplant systemic inflammation as manifested by elevated serum CRP level independently predicts the risk of acute rejection after renal transplantation and may be useful in stratifying patients at the time of transplantation according to immunological risk. Thus, assessment of pretransplant systemic inflammatory status may be helpful in prospective individualization of immunosuppression therapy after renal transplantation.

Does increased urinary interleukin-1 receptor antagonist/interleukin-1beta ratio indicate good prognosis in renal transplant recipients?

BACKGROUND

Interleukin-1 (IL-1) is produced by activated monocytes/macrophages; highly increased amounts of IL-1 have been found in renal tissue in acute rejection of renal grafts. The endogenous inhibitor of IL-1, interleukin-1 receptor antagonist (IL-1ra), is produced in many cells in response to the same stimulus as IL-1. There is some evidence that the balance between IL-1 and IL-1ra is important in the regulation of inflammatory responses. In many inflammatory diseases in both humans and animals, a high concentration of endogenous IL-1ra or administration of exogenous IL-1ra has been shown to relate to shorter recovery time or to reduced mortality.

METHODS

We measured the urinary excretion of IL-1ra and IL-1beta during the first 3-6 posttransplant weeks in 23 patients with acute rejection (69 24-hr urine samples) and in 17 patients with stable graft function (51 24-hr urine samples) and expressed the results as cytokine/creatinine ratios.

RESULTS

Within the follow-up time, patients with rejection had higher urinary IL-1beta/creatinine (ng/mmol) ratios (median 5.0 vs. 2.7; P<0.005), lower IL-1ra/creatinine (ng/mmol) ratios (median 18.1 vs. 34.2; P<0.1), and consequently lower IL-1ra/IL-1beta ratios (median 3.6 vs. 20.3, P<0.005), compared with patients without rejection. In rejecting patients, IL-1ra/creatinine was constantly low and decreased even further during acute rejection, whereas IL-1beta/creatinine ratios increased from a median prerejection value of 3.5 (range not measurable to 9.0) to a median value of 8.1 (P<0.0005) (range 1.6 to 18.3) during rejection.

CONCLUSION

These results suggest that patients who produce high amounts of IL-1ra in relation to IL-1beta are less prone to acute allograft rejection than patients with low IL-1ra/IL-1beta ratios.

False increase in C-reactive protein attributable to heterophilic antibodies in two renal transplant patients treated with rabbit antilymphocyte globulin

Increased serum C-reactive protein (sCRP) is a sensitive marker of renal graft rejection. We describe the cases of two children with uncomplicated renal transplantation who had false-positive sCRP values on analyzers using rabbit anti-CRP but values within the reference range with anti-CRP from other animal species. Cross-reaction with heterophilic antibodies was suggested by clinical and biological signs of serum sickness and daily treatment with rabbit antilymphocyte globulin (ALG). The interference depended on the serum concentration of the cross-reactant and was removed by subtotal IgG adsorption to Protein A or Protein G or by immunoadsorption using rabbit ALG or total IgG in non-immune rabbit serum. Anti-rabbit IgG and IgM antibodies were detected in both patients. These are the first reported cases of cross-reaction with heterophilic antibodies in a turbidimetric CRP assay.

Renal graft rejection or urinary tract infection? The value of myeloperoxidase, C-reactive protein, and alpha2-macroglobulin in the urine

Previous investigations have shown that the determination of two acute-phase proteins in the urine, C-reactive protein (CRPu) and alpha2-macroglobulin (alpha2-MGu), allows a noninvasive diagnosis of acute renal graft dysfunction. A reliable differentiation between rejection and urinary tract infection can be made only when considering the C-reactive protein in serum and urine at the same time (CRPs:CRPu ratio). Therefore, a diagnostic procedure independent of parameters other than urinary proteins is needed. As granulocytes play only a minor role in graft rejection but are a common feature in urinary tract infection, we determined a marker of granulocytes (myeloperoxidase) in urine (MPOu). Eighty-nine renal transplant recipients were included in the study. In normal courses, CRPu, alpha2-MGu, and MPOu were within the normal range. In 15 cases of acute interstitial rejection, an increased excretion of CRPu and alpha2-MGu could be confirmed, but MPOu could not be detected. On the occasion of acute vascular rejection (n=6), with the exception of one case, MPOu could not be observed. The pattern of the three urinary proteins differed in urinary tract infections (n=40): MPOu could be detected in all cases, CRPu in 50% of cases, and alpha2-MGu in 73% of cases. In patients with cytomegalovirus infection (n=7), no MPOu, CRPu, or alpha2-MGu was found. In conclusion, the simultaneous measurement of the three proteins allows a complete, noninvasive, differential diagnostic procedure of renal graft dysfunction.