Sequential monitoring of intragraft cytokine mRNA expression in relation to diastolic left ventricular wall thickness and function early after heart transplantation

Because production of immune regulatory proteins may play a role in early graft dysfunction after heart transplantation, we analyzed whether intragraft cytokine messenger RNA (mRNA) expression levels are associated with diastolic left ventricular function in cardiac allografts. We intensively monitored 16 cardiac allograft recipients during the first 3 months after transplantation. The mRNA expression levels of tumor necrosis factor (TNF-alpha), monocyte chemoattractant protein-1 (MCP-1), transforming growth factor (TGF-beta), platelet derived growth factor (PDGF-A), and basic fibroblast growth factor (bFGF) were measured in endomyocardial biopsies (n = 123) by quantitative RT-PCR. To determine diastolic allograft function, concurrent M-mode and two-dimensional Doppler echocardiograms were analyzed for the following parameters: left ventricular total wall thickness, maximal early and atrial mitral flow velocity, deceleration time of maximal early mitral flow velocity, and isovolumetric relaxation period. During the first 3 months post-transplant an overall decrease in mRNA expression levels of almost all measured cytokines was observed, which paralleled an improvement in diastolic left ventricular wall thickness and function. However, no straightforward relationship could be found between a specific cytokine mRNA expression pattern and the studied echocardiographic parameters. Our data suggest that the improvement in diastolic left ventricular function is associated with a general reduction of inflammation within the allograft, rather than related to a specific cytokine expression pattern.

Inhibition of the IL-15 pathway in anti-CD25 mAb treated renal allograft recipients

Anti-CD25 mAb's are used for prophylaxis of rejection in allograft transplantation. These agents target the alpha-chain, part of the IL-2Ralphabetagamma complex. The beta- and gamma-chain are signaling components that are not specific for IL-2. The T-cell growth factors IL2, IL-7 and IL-15 utilize the gamma-chain and IL-2 and IL-15 share the beta-chain. We have studied the consequences of targeting the IL-2R alpha-chain with the anti-CD25 mAb basiliximab by measuring the IL-2R alphabetagamma expression levels and the IL-2, IL-7 and IL-15 driven proliferation. By flowcytometry and limiting dilution analysis, the IL-2R complex was analyzed in peripheral blood samples from renal allograft recipients (n = 29) who received basiliximab (20 mg IV bolus on day 0 and 4), cyclosporin and mycophenolate mofetil. In peripheral blood, after induction therapy with basiliximab, no CD25 positive T-cells were detectable for 61 days (median, range 25-93 days). When CD25 cells were covered with basiliximab, the percentage and the mean fluorescence intensity (MFI) of IL-2Rbeta positive T-cells significantly decreased, P = 0.02 and P = 0.013, respectively, whereas the expression level of the IL-2Rgamma was not affected. The inhibition of the expression of the IL-2R alpha- and beta-chain had significant consequences for the function of these cells. Both the IL-2- and the IL-15-dependent proliferation were inhibited, P = 0.007 and P = 0.01, respectively. The control, the IL-7 driven proliferation, was not influenced by basiliximab. In conclusion, therapy with anti-CD25 mAb's affect T-cell-dependent allogeneic immune responses, not only by blocking IL-2 signaling but also by impairing IL-15 signaling through downregulating the IL-2/IL-15 receptor beta-chain.

The presence of immune stimulatory cells in fresh and cryopreserved donor aortic and pulmonary valve allografts

BACKGROUND AND AIM OF THE STUDY

Heart valve allografts (HVA) used for valve replacement or ventricular outflow tract reconstruction may suffer from structural deterioration due to donor-specific immune responses. The presence of immune stimulatory cells, including dendritic cells and activated endothelial cells, has not been studied thoroughly in aortic or pulmonary HVA. The presence and distribution of these cells in both aortic and pulmonary HVA, before and after cryopreservation, was analyzed immunohistochemically.

METHODS

Aortic (n = 16) and pulmonary (n = 13) HVA, discarded for implantation due to morphological or technical reasons, were obtained from 12 heart-beating and nine non-heart-beating tissue donors. Aortic and pulmonary HVA were dissected longitudinally into two symmetric sections by splicing of the non-coronary aortic and non-facing pulmonary cusps. Each symmetric half contained one-and-a-half valve cusps attached to the vascular wall. Fresh halves were directly fixed in formaldehyde, and analyzed immunohistochemically. The corresponding halves of the valves were decontaminated, cryopreserved, stored for at least three weeks and thereafter thawed according to the Heart Valve Bank protocol before analysis.

RESULTS

Activated endothelial cells, expressing PECAM-1 (CD31), VCAM-1 and HLA class II molecules covered at least 50% of fresh valvular surfaces. A comprehensive vascular network was found in the myocardial rim and adventitial layer, which was covered entirely by activated endothelial cells. HLA class II-positive macrophages (CD68) and T lymphocytes (CD3) were found scattered in the stroma and subendothelial layer of the valve leaflets. Mononuclear cell clusters were found predominantly in relation to native degenerative foci, and more often in aortic valves. No difference in cellular distribution was observed between the two donor types. Dendritic cells positive for both S100 and CD45 were not found in immuno-double-stained sections. Cryopreservation resulted in minor structural alterations in the vascular wall, and an increase of cells with pycnotic nuclei and reduction of adhesion molecule expression on endothelial cells. All fresh and cryopreserved aortic and pulmonary HVA contained abundant HLA class II-positive endothelial cells and sparse distribution of mononuclear cells in the luminal and adventitial layers.

CONCLUSION

Cryopreservation minimally affected the extracellular matrix of HVA and diminished the cellularity of the valve graft, while the HLA class II expression of cells was not abrogated. Aortic valve allografts harbor more mononuclear cells than their pulmonary counterparts. The absence of dendritic cells (professional antigen-presenting cells) is compensated by the preservation of other cells expressing HLA class II molecules predominantly in the endothelium; this may be responsible for the initiation of a specific immune response against HVA.

Effect of HLA-DR matching on acute rejection after clinical heart transplantation might be influenced by an IL-2 gene polymorphism

BACKGROUND

To examine whether genetic factors are involved in the development of acute rejection (AR), we investigated a (CA)m(CT)n repeat in the 3'-flanking region of the interleukin (IL)-2 gene.

METHOD

We genotyped 290 heart transplant recipients with and without AR (International Society for Heart and Lung Transplantation criteria > or =3A) and 101 controls.

RESULTS

The frequency of allele 135 of the repeat and its genotype distribution (carriers/noncarriers) were significantly associated with freedom from AR (P=0.03 and P=0.02, respectively). We also found interaction between allele 135 and HLA-DR matching. More carriers of allele 135 with no or one mismatch remained free from AR compared to patients without the allele (P=0.01). This was not found in the HLA-DR group with two mismatches.

CONCLUSION

HLA-DR matching might only be effective in reducing AR after heart transplantation in recipients who carry allele 135 of the (CA)m(CT)n repeat in the 3'-flanking region of the IL-2 gene.

Prediction of mortality in heart transplant recipients by stress technetium-99m tetrofosmin myocardial perfusion imaging

Cardiac allograft vasculopathy is a major cause of mortality in heart transplant recipients. The aim of this study was to assess the prognostic value of stress myocardial perfusion imaging in heart transplant recipients. We studied 166 patients (age 54 +/- 10 years, 140 men) by symptom-limited bicycle exercise or dobutamine (up to 40 microg/kg/min) stress myocardial perfusion imaging 7.4 +/- 2.5 years after heart transplantation. An intravenous dose of 370 MBq of technetium-99m tetrofosmin was injected at peak stress and 24 hours after the stress test. An abnormal test was defined as reversible or fixed perfusion defects. Perfusion abnormalities were detected in 55 patients (33%). During a median follow-up of 2.5 years, 54 deaths (33%) occurred, 16 of which were due to cardiac causes. The incidence of perfusion abnormalities was higher in patients with subsequent cardiac death than in patients without subsequent cardiac death (69% vs 29%, p = 0.01). In an incremental multivariate Cox analysis, cardiac death was not predicted by age, gender, duration of transplantation, number of rejection episodes, or cytomegalovirus infection. In the next step, stress test parameters were added. The peak rate-pressure product was the only significant predictor at this step (risk ratio 0.84, 95% confidence interval 0.73 to 0.97, chi-square 7.7, p = 0.006). In the final step, the presence of abnormal myocardial perfusion was an independent predictor of cardiac death (risk ratio 3.5, 95% confidence interval 1.6 to 11.7, chi-square 4.7, incremental to clinical and stress test variables, p = 0.01). It is concluded that stress myocardial perfusion imaging with technetium-99m tetrofosmin single-photon emission computed tomography provides incremental data for the prediction of cardiac death in heart transplant recipients.

Intragraft interleukin 2 mRNA expression during acute cellular rejection and left ventricular total wall thickness after heart transplantation

OBJECTIVE

To assess whether diastolic graft function is influenced by intragraft interleukin 2 (IL-2) messenger RNA (mRNA) expression in rejecting cardiac allografts.

DESIGN

16 recipients of cardiac allografts were monitored during the first three months after transplantation. The presence of IL-2 mRNA in endomyocardial biopsies (n = 123) was measured by reverse transcriptase polymerase chain reaction. To determine heart function, concurrent M mode and two dimensional Doppler echocardiograms were analysed.

RESULTS

Histological signs of acute rejection (International Society for Heart and Lung Transplantation (ISHLT) rejection grade > 2) were strongly associated with IL-2 mRNA expression (IL-2 mRNA was present in 12 of 20 endomyocardial biopsies (60%) with acute rejection and in 24 of 103 endomyocardial biopsies (23%) without acute rejection, p = 0.002). No significant relation was found between either histology or IL-2 mRNA expression alone and the studied echocardiographic parameters. However, stratification of the echocardiographic data into those of patients with and those without acute rejection showed that during acute rejection IL-2 mRNA expression was significantly associated with increased left ventricular total wall thickness (mean change in total wall thickness was +0.22 cm in patients with IL-2 mRNA expression versus -0.18 cm in patients without IL-2 mRNA expression, p = 0.048).

CONCLUSIONS

An increase in left ventricular total wall thickness precedes IL-2 positive acute rejection after heart transplantation. Thus, cardiac allograft rejection accompanied by intragraft IL-2 mRNA expression may be indicative of more severe rejection episodes.

TGF-beta1 gene polymorphisms in patients with end-stage heart failure

BACKGROUND

The regulatory cytokine transforming growth factor (TGF)-beta1 is thought to play a role in atherosclerotic heart disease as well as in idiopathic cardiomyopathy. The production of TGF-beta1 is genetically controlled as polymorphisms in the signaling sequence of the TGF-beta1 gene leucine(10)-->proline and arginine(25)-->proline are involved in the regulation of the protein production level. We investigated whether these polymorphisms are associated with end-stage heart failure caused by dilated cardiomyopathy (CMP) or ischemic heart disease (IHD).

METHODS

We determined polymorphisms using sequence specific oligonucleotide probing (SSOP) in genomic DNA samples from heart transplant recipients (n = 253) and controls (n = 94). Indications for transplantation were dilated CMP (n = 109) and IHD (n = 144).

RESULTS

We found a difference in TGF-beta1 codon 10 genotype distribution among patients with IHD, dilated CMP, and controls (p = 0.034; chi(2) test). Patients with dilated CMP differed from patients with IHD (p = 0.044) and healthy controls (0.017). The genotype distribution between patients with IHD and controls was comparable. For codon 25, we found no difference in genotype distribution.

CONCLUSIONS

The Leu(10)-->Pro (codon 10) polymorphism in the TGF-beta1 gene is associated with end-stage heart failure caused by dilated CMP and not with IHD. This observation suggests that TGF-beta1 is involved in the pathogenesis of CMP.

Conversion from cyclosporin A to tacrolimus is safe and decreases blood pressure, cholesterol levels and TGF-beta 1 type I receptor expression

To determine whether conversion from cyclosporin A (CsA) to tacrolimus (TAC)-based immunosuppressive therapy is safe and might lead to improvement in the clinical side effect profile we studied 55 cardiac allograft recipients. Ten stable patients were electively converted (0.2-1.5 yr after transplantation; group I) and 45 patients were converted on indication (0.5-14 yr after transplantation; group II). We studied blood pressure, cholesterol level and renal function in all patients. To unravel the mechanisms by which CsA may exert its toxic effects and to evaluate whether conversion is associated with immune activation, we analyzed the transforming growth factor (TGF)-beta 1 system and intragraft interleukin (IL)-2 and IL-15 mRNA expression by real-time reverse transcription-polymerase chain reaction (RT-PCR) and quantitative flow cytometry in the selectively converted patients (group I). Conversion did not result in immune activation as no clinical, histological or molecular signs of immune activation (increased intragraft IL-2 and IL-15 messenger RNA (mRNA) expression) leading to rejection were found. It did not improve renal function neither in patient group I nor in patient group II. However, after conversion the blood pressure decreased (group I: systolic 154+/-16 vs 143+/-21 mmHg, p=0.03, diastolic: 99+/-11 vs 90+/-11, p=0.02 and group II: systolic 155+/-17 vs 142+/-14, p<0.001, diastolic: 99+/-11 vs 91+/-8 mmHg, p<0.001). Likewise, the cholesterol levels improved (group I: 6.6+/-0.5 vs 5.7+/-0.3 mmol/L, p=0.001 and group II: 7.1+/-1.7 vs 6.1+/-1.7 mmol/L, p=0.001). When patients were treated with TAC the ongoing rejections (n=4) resolved and gum hyperplasia disappeared (n=5). Conversion was associated with a two-fold lower TGF-beta 1 type I receptor expression on peripheral lymphocytes and monocytes (p=0.02 and p=0.002, respectively). Conversion from CsA to TAC results in improvement of blood pressure and cholesterol levels and does not induce immune activation. These beneficial effects were accompanied with lower TGF-beta 1 type I receptor expression.

T cells activate the tumor necrosis factor-alpha system during hemodialysis, resulting in tachyphylaxis

BACKGROUND

The immunosuppressive state of hemodialysis (HD) patients is accompanied by activation of antigen-presenting cell-derived cytokines, for example, tumor necrosis factor-alpha (TNF-alpha), which are required for T-cell activation. To test whether an activated TNF-alpha system results in impaired T-cell response in these patients, we analyzed parameters of their antigen-presenting cell (APC) function (for example, TNF-alpha system) and T-cell function [for example, interleukin-2 (IL-2) system].

METHODS

By quantitative flow cytometry, the expression of the TNF-receptor 2 (TNF-R2 = CD120b) and the alpha and beta chain of the IL-2 receptor (IL-2R; CD25, CD122) was measured. Using reverse transcriptase-polymerase chain reaction, the mRNA for TNF-alpha, IL-2, and IL-2R were determined. Phyto-hemagglutinin (PHA)- and IL-2-stimulated proliferation and cytokine production were measured. Biological activity of soluble receptors was measured by adding recombinant cytokines to the patient's plasma.

RESULTS

CD120b expression was significantly increased in HD patients, whereas CD25 and CD122 was comparable to controls. In contrast to mRNA for IL-2 and IL-2R, mRNA for TNF-alpha was increased in HD. This resulted in significantly increased TNF-alpha levels in HD patients. In peripheral blood of HD patients, high levels of soluble TNF-R (R1 and R2) and IL-2R were found. These receptors were capable of binding 40% of added TNF-alpha and 55% of added IL-2. PHA-induced TNF-alpha production by T cells from HD patients was significantly lower, while their PHA-stimulated IL-2 production and proliferation capacity by T cells were comparable to controls.

CONCLUSIONS

We conclude that although the TNF-alpha system is activated during HD, the TNF-alpha production of T cells is impaired, suggesting that tachyphylaxis of T cells occurs for TNF-alpha, as their proliferative capacity and IL-2 production capacity do not imply an intrinsic T-cell defect.

Quantitative flow cytometry shows activation of the TNF-alpha system but not of the IL-2 system at the single cell level in renal replacement therapy

BACKGROUND

Immunological dysfunction in patients on haemodialysis may be related to imbalanced cytokine systems, such as tumour necrosis factor (TNF)-alpha and interleukin (IL)-2. Despite activation of these systems, haemodialysis patients show high susceptibility for infections and malignancies, and have a poor immunological reaction to T-cell-dependent antigens, like hepatitis B vaccination. In this study we have determined the activation status of the two different cytokine systems, at the single cell level, using quantitative flow cytometry.

METHODS

Using fluorescein isothiocyanate- or phycoerythrin-conjugated antibodies directed against TNF-R2 (CD120b), IL-2Ralpha (CD25) and IL-2Rbeta (CD122), we measured the expression of these receptors at the single cell level in order to determine the level of activation of monocytes and T-lymphocytes.

RESULTS

Significantly higher expression of the TNF-alpha receptor, TNF-R2, was present on both monocytes and T-lymphocytes in patients on renal replacement therapy (RRT) compared with pre-dialysis chronic renal failure (CRF) patients and controls, indicating activation of the TNF-alpha system. In contrast, IL-2R expression was comparable in all groups studied, which may reflect a non-activated state of the IL-2 system.

CONCLUSIONS

The present study illustrates an activated state of the TNF-alpha system in patients on RRT, at the single cell level, while the IL-2 system seems to be unaffected. These findings support the hypothesis that the interaction between the TNF-alpha and IL-2 cytokine systems is disturbed.

Quantitative flow cytometry to measure the TNF-alpha and IL-2 system after heart transplantation

After heart transplantation a high incidence of infections and malignancies is found. Not only immunosuppression, but also intrinsic cytokine systems with some unbalance, e. g. TNF-alpha and IL-2, can result in impaired immune competence and may have a role in these complications. The aim of this study was to assess the activity of the TNF-alpha and IL-2 systems after heart transplantation. In peripheral blood we measured expression of activation markers of TNF-alpha (TNF-R2) and IL-2 (IL-2R alpha, IL-2R beta-chain) on monocytes and lymphocytes using quantitative flow-cytometric analysis. TNF-R2 expression was significantly enhanced on monocytes and lymphocytes in patients after heart transplantation, while the expression of IL-2R alpha and IL-2R beta was not elevated. Increased TNF-R2 expression in peripheral blood after heart transplantation reflects an activated TNF-alpha system, leading to high levels of active sTNF-R, which impairs TNF-alpha bioavailibility and consequently leads to immune incompetence.

The transforming growth factor-beta1 codon 10 gene polymorphism and accelerated graft vascular disease after clinical heart transplantation

BACKGROUND

The multifunctional cytokine transforming growth factor- (TGF) beta1 is thought to play a role in the pathogenesis of graft vascular disease (GVD). Polymorphisms at codon 10, (Leu10-->Pro) and codon 25 (Arg25-->Pro) in the signal sequence of the TGF-beta1 gene regulate the production and secretion of the protein. We investigated whether these polymorphisms are risk factors for the development of GVD after clinical heart transplantation.

METHOD

TGF-beta1 polymorphisms, Leu10-->Pro and Arg25-->Pro, were determined in DNA from heart transplant recipients (n=252) and their donors (n=213), using sequence-specific oligonucleotide probing. GVD was angiographically diagnosed 1 year after transplantation. In addition other potential risk factors including underlying disease, recipient and donor age, recipient and donor gender, number of acute rejections in the first year, cold ischemia time, and HLA mismatches were analyzed by univariate and multivariate logistic regression analysis.

RESULTS

Univariate analysis showed that the recipient TGF-beta1 polymorphism Leu10-->Pro, (P=0.056, chi2 test), underlying disease (P=0.01, chi2 test), number of acute rejections in the first-year (P=0.03, analysis of variance), and donor age (P<0.001, analysis of variance) were risk factors for the development of GVD. The TGF-beta1 Arg25-->Pro polymorphism was not a risk factor. Also in the multivariate analysis, the recipient TGF-beta1 codon 10 polymorphism was associated with GVD, with patients homozygous for Pro at greatest risk (odds ratio 7.7, P=0.03). Apart for the recipient TGF-beta1 Leu10-->Pro polymorphism, donor age appeared to be an independent risk factor for the development of GVD at 1 year. Patients with older donor hearts were at greater risk than patients receiving grafts from younger donors (odds ratio 1.1/year, P<0.001).

CONCLUSION

Recipient TGF-beta1 Leu10-->Pro polymorphism and higher donor age are independent risk factors for the development of GVD after clinical heart transplantation.

Failure to down-regulate intragraft cytokine mRNA expression shortly after clinical heart transplantation is associated with high incidence of acute rejection

BACKGROUND

Brain-death, ischemia and reperfusion damage have been implicated as initial factors that lead to a cascade of immunologic events that result in allograft rejection in experimental animals. Cytokines are thought to play a central role in this process. Therefore, we evaluated intragraft cytokine mRNA expression at an early stage after clinical heart transplantation and related these data to ischemia, immunosuppression, and rejection.

METHODS

We sampled endomyocardial biopsies at 30 minutes (EMB 0) and at 1 week (EMB 1) after transplantation from 20 cardiac allograft recipients. Intragraft monocyte chemoattractant protein (MCP-1) and basic fibroblast growth factor (bFGF) mRNA expression levels were quantitatively measured using competitive template Reverse-transcriptase polymerase chain reaction (RT-PCR).

RESULTS

We measured significantly lower MCP-1 and bFGF mRNA expression levels in EMB 1 compared with EMB 0 (MCP-1, p = 0.006; bFGF, p = 0.019). We found no direct correlation between the cytokine mRNA expression levels in EMB 0 or EMB 1 and ischemic times, induction therapy, or cyclosporine whole-blood trough levels. Patients with a high incidence of acute rejection episodes (>2 in the first year) had higher bFGF mRNA expression levels (p = 0.009) and comparable MCP-1 mRNA expression levels (p = 0.378) at 1 week, compared with patients with a lower rejection incidence. The MCP-1 and bFGF mRNA expression levels in the first week were not associated with the development of graft vascular disease in the first year post-transplant.

CONCLUSIONS

We found a significant decrease of intragraft MCP-1 and bFGF mRNA expression levels in the first post-operative week. Patients with a high incidence of acute rejection had higher bFGF mRNA expression levels in their first week biopsy. Therefore, we conclude that patients who fail to down-regulate their bFGF mRNA expression early after transplantation are at higher risk for acute rejection.

Discrepancy between mRNA expression and production of IL-2 and IL-4 by cultured graft infiltrating cells propagated from endomyocardial biopsies

We studied whether acute rejection correlated with the cytokine production pattern and mRNA expression of interleukin-2 (IL-2) and interleukin-4 (IL-4) in lymphocyte cultures derived from endomyocardial biopsies (EMB) that were stimulated with B cell lines of donor origin. Unstimulated biopsy cultures neither expressed mRNA nor produced IL-2 or IL-4. All stimulated biopsy cultures contained mRNA transcripts for IL-2 and IL-4. In contrast, we found different IL-2 and IL-4 production patterns. Within the first 90 days after heart transplantation (HTx), higher levels of IL-4 were measured in cultures derived from EMB with myocytolysis than in cultures from EMB without signs of myocytolysis. More than 90 days after HTx, this phenomenon was reversed and more IL-4 was produced in cultures derived from EMB without myocytolysis. These differences were not detected for IL-2 production.

T cells activate the tumor necrosis factor-alpha system during hemodialysis, resulting in tachyphylaxis

BACKGROUND

The immunosuppressive state of hemodialysis (HD) patients is accompanied by activation of antigen-presenting cell-derived cytokines, for example, tumor necrosis factor-alpha (TNF-alpha), which are required for T-cell activation. To test whether an activated TNF-alpha system results in impaired T-cell response in these patients, we analyzed parameters of their antigen-presenting cell (APC) function (for example, TNF-alpha system) and T-cell function [for example, interleukin-2 (IL-2) system].

METHODS

By quantitative flow cytometry, the expression of the TNF-receptor 2 (TNF-R2 = CD120b) and the alpha and beta chain of the IL-2 receptor (IL-2R; CD25, CD122) was measured. Using reverse transcriptase-polymerase chain reaction, the mRNA for TNF-alpha, IL-2, and IL-2R were determined. Phyto-hemagglutinin (PHA)- and IL-2-stimulated proliferation and cytokine production were measured. Biological activity of soluble receptors was measured by adding recombinant cytokines to the patient's plasma.

RESULTS

CD120b expression was significantly increased in HD patients, whereas CD25 and CD122 was comparable to controls. In contrast to mRNA for IL-2 and IL-2R, mRNA for TNF-alpha was increased in HD. This resulted in significantly increased TNF-alpha levels in HD patients. In peripheral blood of HD patients, high levels of soluble TNF-R (R1 and R2) and IL-2R were found. These receptors were capable of binding 40% of added TNF-alpha and 55% of added IL-2. PHA-induced TNF-alpha production by T cells from HD patients was significantly lower, while their PHA-stimulated IL-2 production and proliferation capacity by T cells were comparable to controls.

CONCLUSIONS

We conclude that although the TNF-alpha system is activated during HD, the TNF-alpha production of T cells is impaired, suggesting that tachyphylaxis of T cells occurs for TNF-alpha, as their proliferative capacity and IL-2 production capacity do not imply an intrinsic T-cell defect.

Renal failure after clinical heart transplantation is associated with the TGF-beta 1 codon 10 gene polymorphism

BACKGROUND

To determine whether genetic factors are involved in the development of renal dysfunction due to cyclosporine nephrotoxicity, we analyzed 2 polymorphisms in the signal sequence of the transforming growth factor (TGF)-beta 1 gene; codon 10 (Leu(10) --> Pro) and codon 25 (Arg(25) --> Pro).

METHOD

Using sequence specific oligonucleotide probing, we analyzed both TGF-beta1 gene polymorphisms in cardiac allograft recipients (n = 168) who survived at least 1 year with minimal follow-up of 7 years. Patients received cyclosporine and steroids as maintenance immunosuppressive therapy. Renal dysfunction was defined as a serum creatinine > or = 250 micromol/liter.

RESULTS

Renal dysfunction was observed in 2% (3/168) of the patients at 1 year, in 7% (11/160) at 3 years, in 12% (18/152) at 5 years, and in 20% (26/131) at 7 years post-transplantation. The genotypic distributions for TGF-beta1 codon 10 were 7% Pro/Pro, 61% Pro/Leu, and 32% Leu/Leu, and for codon 25 these percentages were 1% Pro/Pro, 12% Pro/Arg, and 87% Arg/Arg. We found an association between the TGF-beta 1 genotype encoding proline at codon 10 and renal dysfunction. At 7 years post-transplantation, 26% (23/89) of the patients with the heterozygous Pro/Leu or homozygous Pro/Pro genotype had renal dysfunction vs only 7% (3/42) of the patients with the homozygous Leu/Leu genotype (p = 0.017). For the TGF-beta1 codon 25 genotypes, we found no association between TGF-beta 1 genotypes and renal dysfunction.

CONCLUSION

Our data support the hypothesis that TGF-beta 1 is involved in the process leading to renal insufficiency in cyclosporine-treated cardiac allograft recipients. In these patients the presence of TGF-beta 1 Pro(10) might be a risk factor.

Functional responses of T cells blocked by anti-CD25 antibody therapy during cardiac rejection

BACKGROUND

Despite anti-CD25 (interleukin [IL]-2 receptor alpha chain) monoclonal antibody (mAb) therapy, rejection can still occur. T-cell activation through the IL-2 receptor beta and gamma chains by IL-2 or other growth factors may contribute to this rejection. Recently, we have demonstrated that the T-cell growth factor IL-15 was abundantly present in rejecting cardiac grafts during anti-CD25 mAb treatment.

METHODS

To test whether IL-2- and IL-15-responsive T cells play an active role in rejection during anti-CD25 mAb therapy, we measured the frequency of IL-2- and IL-15-proliferative T cells in peripheral blood from treated patients during rejection (n=12). Measurements were made by limiting dilution analysis in the absence and presence of extra in vitro-added mouse anti-human CD25 mAb.

RESULTS

In the absence of anti-CD25 mAb, the frequencies of peripheral T cells responding to recombinant human (rh)IL-2 and rhIL-15 from patients were lower than those measured in samples of healthy controls (n=7): median of IL-2-responding T cells 78 per 10(6) (range 31-210 per 10(6)) vs. 154 per 10(6) (122-484 per 10(6), P=0.008) and median of IL-15-responding T cells 62 per 10(6) (range 19-207 per 10(6)) vs. 129 per 10(6) (range 79-192 per 10(6), P=0.02), respectively. In the presence of extra in vitro-added anti-CD25 mAb, frequencies of IL-2-responding T cells from patients significantly decreased, although a considerable number of T cells still proliferated on rhIL-2 (median 85%, range 46-100%). In contrast, the frequencies of IL-15 T cells still responding remained stable (median 2%, range 0-50%, P<0.001).

CONCLUSIONS

Treatment with anti-CD25 mAbs cannot provide complete suppression of T-cell function because significant numbers of IL-2- and IL-15-responsive T cells remain present in the peripheral blood of allograft recipients during anti-CD25 mAb treatment.

TNF-alpha: mRNA, plasma protein levels and soluble receptors in patients on chronic hemodialysis, on CAPD and with end-stage renal failure

BACKGROUND

Patients on hemodialysis suffer from an impaired immunity against infectious agents, hyporesponsiveness to vaccination and are prone to develop malignancies. This clinical state of immunoincompetence may be due to a disbalance in their defense mechanisms in which TNF-alpha and its soluble receptors 1 and 2 play a central role.

PATIENTS AND METHODS

We measured, with double-sandwich ELISA, the levels of TNF-alpha and the soluble TNF-receptors in peripheral blood of patients on chronic intermittent hemodialysis (CIHD), on peritoneal dialysis (CAPD) and pre-dialysis end-stage renal failure (ESRF). Using reverse transcriptase polymerase chain reaction (RT-PCR) analysis, we quantified the amount of TNF-alpha mRNA in peripheral blood mononuclear cells (PBMC) obtained from these patient groups.

RESULTS

In none of the patient groups, elevated levels of TNF-alpha were detected with ELISA, while high levels of soluble TNF receptors were present in ESRF, CAPD and CIHD patients. This may be the result of an activated TNF-alpha system or due to their impaired renal clearance. TNF-alpha mRNA level was elevated in CIHD patients compared to ESRF and CAPD patients or healthy controls.

CONCLUSION

This suggests that only during chronic HD is the TNF-alpha system activated. High levels of sTNFR, found in ESRF or CAPD patients do not reflect activation of TNF-alpha system, but are the result of impaired renal clearance of the receptors. Indeed, we found a strong linear correlation between the levels of sTNF receptors and renal function. Nevertheless, these high levels of sTNF receptors are biological active, as they were able to bind active TNF-alpha up to 75% (range 46 - 83%) and thus inhibit the bioactivity and bioavailability of produced TNF-alpha. This may play a role in the immunoincompetence of these patients.

Intragraft platelet-derived growth factor-alpha and transforming growth factor-beta1 during the development of accelerated graft vascular disease after clinical heart transplantation

This study was to determine whether the growth factors platelet-derived growth factor-alpha (PDGF-alpha) and transforming growth factor-beta1 (TGF-beta1) contribute to the development of graft vascular disease (GVD) after clinical heart transplantation. We analysed intragraft PDGF-alpha and TGF-beta1 messenger RNA (mRNA) expression levels by competitive template reverse transcriptase polymerase chain reaction (RT-PCR). Endomyocardial biopsies (EMB) were obtained at 1 and 9 months post-transplant from cardiac allograft recipients with (n = 11) and without (n = 11) angiographic evidence of GVD at 1 year. In 1-month EMB, comparable TGF-beta1 mRNA levels were found in patients with and without GVD at 1 year (p = 0.84, Mann-Whitney U-test). In contrast, in 9-month EMB during the development of GVD, intragraft mRNA levels of both PDGF-alpha (p = 0.08) and TGF-beta1 (p = 0.03) were higher in patients with GVD after the first year compared to patients without GVD. These results suggest that intragraft PDGF-alpha and TGF-beta1 play a role in the pathogenesis of accelerated GVD after clinical heart transplantation.

The TNF-alpha system in heart failure and after heart transplantation: plasma protein levels, mRNA expression, soluble receptors and plasma buffer capacity

BACKGROUND

The two soluble tumour necrosis factor (TNF) receptors (sTNF-R1, sTNF-R2) can bind TNF-alpha, which is a cytokine with cardiodepressant properties. In heart failure and after heart transplantation, the TNF-alpha system is unbalanced, due to elevated levels of sTNF receptors.

AIM

To assess the activity of the TNF-alpha system in patients with heart failure and after heart transplantation.

METHODS

We measured TNF-alpha mRNA expression of peripheral blood mononuclear cells, plasma levels of TNF-alpha and sTNF reverse transcriptase receptors, using polymerase chain reaction and ELISA and performed a TNF-alpha binding capacity analysis, quantitating the buffer capacity of patients' plasma.

RESULTS

In 11 patients with heart failure and in 15 cardiac allograft recipients, the TNF-alpha mRNA expression was comparable to controls. This level of mRNA was not accompanied by detectable TNF-alpha plasma levels. Significantly higher sTNF receptors levels were found in patients: ( P <0.001; ANOVA). The TNF-alpha binding capacity of patients' plasma was significantly increased, which led to decreased TNF-alpha recovery ( P<0.05). Both sTNF receptors showed a linear correlation with serum creatinine (sTNF-RI: r=0.92; sTNF-R2: r=0.82, P<0.001).

CONCLUSIONS

The TNF-alpha mRNA expression and plasma levels show that the 'peripheral' TNF-alpha system is not activated. The high sTNF-receptors levels and their elevated TNF-alpha binding capacity, resulting in decreased TNF-alpha bioavailability, may contribute to an immunosuppressed state in these patients.

Anti-CD25 therapy reveals the redundancy of the intragraft cytokine network after clinical heart transplantation

BACKGROUND

Despite blockade of the interleukin-2/interleukin 2 receptor (IL-2/IL-2R) pathway by the murine anti-CD25 (i.e., IL-2R alpha chain) monoclonal antibody BT563, cardiac rejection can still occur. In these cases, growth factors other than IL-2 may contribute to allograft rejection. We studied the expression of IL-15, a macrophage-derived cytokine associated with T-cell activation, which interacts with the beta and gamma chains of the IL-2R during rejection episodes under anti-CD25 therapy.

METHODS

We measured intragraft IL-15 mRNA expression and the number of IL-15- and CD68-positive cells in posttransplantation endomyocardial biopsies (EMBs; n=45) and in nontransplanted, donor-heart specimens (n=11) by competitive template reverse transcription-polymerase chain reaction and immunohistochemistry, respectively.

RESULTS

IL-15 mRNA expression was present in the majority of posttransplantation EMB specimens (91%, 41/45) and in nontransplanted donor-heart specimens (91%, 10/11). Relative IL-15 mRNA levels were neither associated with transplantation nor with rejection status. After transplantation, the number of IL-15- and CD68-positive cells significantly increased (P<0.001), but IL-15-positive cell counts did not reflect the histological rejection grade. Anti-CD25 treatment, in contrast to its effects on the IL-2/IL-2R complex, had no influence on intragraft IL-15 mRNA and protein production. In rejection EMB specimens, during (n=5) and after (n=8) anti-CD25 therapy, no differences in relative IL-15 mRNA levels, or in IL-15- and CD68-positive cell counts, were measured.

CONCLUSIONS

After heart transplantation, high numbers of IL-15- and CD68-positive cells infiltrate the graft. This phenomenon is independent of the rejection status. IL-15 remains present during blockade of the IL-2/IL-2R pathway by anti-CD25 monoclonal antibodies, and it may participate in T cell-dependent donor-directed immune responses, thereby explaining the occurrence of rejection in the absence of IL-2.

Redundancy of the cytokine network in the development of rejection after clinical heart transplantation

We used reverse transcriptase-polymerase chain reaction analysis to study the effects of anti-rejection prophylaxis with an anti-interleukin (IL)-2 receptor (IL-2R) monoclonal antibody (BT563) on the allogeneic process by analyzing intragraft IL-2, IL-4, and IL-15 mRNA expression. Analysis showed an association between rejection and intragraft IL-2 mRNA and IL-4 mRNA transcription, whereas IL-15 was constitutively expressed: IL-2, 62% (8/13) during rejection versus 23% (8/35) during immunological quiescence (P < 0.01); IL-4, 69% versus 23% (P < 0.01). BT563 therapy influenced the intragraft mRNA expression of IL-2 and IL-4 but not of IL-15. In endomyocardial biopsies (EMB) showing rejection, mRNA expression of IL-2 was detectable in 40% (2/5) during BT563 treatment versus 75% (6/8) in the absence of BT563; for IL-4, 23% versus 88%, respectively. In contrast, IL-15 mRNA transcription was not affected. Quantitative analysis in rejection EMB showed comparable IL-15 mRNA levels during and after BT563 treatment. This study demonstrates that therapeutic intervention within the IL-2-dependent T-cell activation cascade does not completely prevent rejection. Other cytokines, such as IL-15, may participate in IL-2-independent rejections.

The TNF-alpha system after successful living-related kidney transplantation

The TNF-alpha system is thought to play a central role in the reduced immunity of haemodialysis patients. The imbalance between the high levels of soluble TNF receptors R1 and R2 and the low levels of immunoactive TNF-alpha results in an increased TNF-alpha buffering capacity leading to reduced immune responses. Apart from impaired renal clearance of the receptors, inefficient TNF-alpha production as a result of the uraemia may also contribute to the imbalance between this cytokine and its receptors. In patients receiving a living-related kidney transplant, renal function is nearly normalized in a very short period. This restoration of renal function may result in a state of better immunocompetence, either as a result of improved clearance of the receptors or as a result of reversal of the uraemic state. To differentiate between these two possibilities, we measured TNF-alpha protein, mRNA and the soluble TNF receptors R1 and R2 before and after successful renal transplantation. TNF-alpha mRNA was not affected by transplantation, indicating constant TNF-alpha production. The imbalance in the TNF-alpha system was markedly improved after transplantation, although normal values of the soluble receptors were not reached. One year after transplantation in stable kidney transplant recipients there was still an imbalance in the TNF-alpha system caused by persistently elevated levels of the soluble TNF-receptors. These results suggest that even after successful kidney transplantation the TNF-alpha system remains activated. However, despite immunosuppressive therapy, recipients of a living-related kidney do have a better balanced TNF-alpha system compared to haemodialysis patients.

Intragraft cytokine gene expression: implications for clinical transplantation

As our knowledge of the cytokine network in experimental transplant models grows, we need to understand how and to what extent cytokines mediate the various donor-directed immune events in clinical situations. This overview of clinical cytokine measurements shows that specific intragraft cytokine messenger RNA (mRNA) expression profiles can be associated with acute rejection, that they may reflect the efficacy of immunosuppression, and that they can identify patients at risk for the development of early chronic rejection. The literature also shows that acute rejection and immunological quiescence in humans are not restricted to the cytokine patterns defined in the type 1/type 2 paradigm. This apparent lack of association may be caused by the immunosuppression used in the clinic but may also be the result of the infinite diversity of donor and recipient factors, in which polymorphisms in cytokines and cytokine receptor genes may play a central role.

Increased intragraft IL-15 mRNA expression after liver transplantation

To study T-cell/macrophage interactions at the molecular level in clinical allograft rejection, we measured intragraft mRNA expression of the T-cell derived cytokine IL-2 and the macrophage derived chemokine IL-15, a novel cytokine associated with T-cell activation, in post-transplant liver biopsies (n = 33) and in non-transplanted control liver tissue by reverse transcriptase-polymerase chain reaction (RT-PCR). We analyzed biopsies without evidence of rejection (n = 12), with spontaneously resolving histological rejection (n = 10), or with histological rejection accompanied with clinical rejection (n = 11) defined by rising serum bilirubin and aspartate amino transaminase levels. IL-15 mRNA expression was present in the majority of post-transplant liver biopsies (91%, 30/33) and was significantly upregulated as compared with non-transplanted liver tissue (p = 0.005). However, the increased intragraft IL-15 mRNA level was not indicative for rejection. In contrast to intragraft IL-15 mRNA expression, IL-2 mRNA transcription was measured in the minority of the post-transplant liver biopsies (15%, 5/33) and not detectable in control specimens. In addition, IL-2 mRNA was almost specifically measured in rejection biopsies concurrent with graft dysfunction (36%, 4/11 versus 1/22 without clinical rejection; p = 0.03). No relation between intragraft IL-2 and IL-15 mRNA expression was found. The IL-15 mRNA expression levels were not higher in the IL-2 negative rejections compared with those in IL-2 positive rejections. To conclude, in contrast to IL-2, the function of IL-15 in T-cell mediated rejection remains unclear. The overall high IL-15 mRNA levels in sites of immune responses suggests that the macrophage-derived mediator IL-15 is involved in a constant flow of T-cells from the circulation into the graft.

The nature of acute rejection is associated with development of graft vascular disease after clinical heart transplantation

BACKGROUND

To determine mechanisms that trigger graft vascular disease (GVD) after heart transplantation, we studied parameters that reflect both early and late intragraft allogeneic reactions.

METHOD

With reverse transcriptase-polymerase chain reaction analysis, mRNA expression of interleukin-2 (IL-2), interleukin-4, interleukin-6, interleukin-10, interferon-gamma, platelet-derived growth factor-alpha, and transforming growth factor-beta was measured in endomyocardial biopsy (EMB) specimens obtained from 34 recipients during the first acute rejection episode (n = 29) or at a comparable time after transplantation for patients without rejection (n = 5) and at time of assessment of GVD by coronary angiography at 1 year (n = 34).

RESULTS

At the time of assessment of GVD, mRNA expression of IL-2, interleukin-4, and interleukin-6 were barely detectable, whereas messenger coding for interferon-gamma, interleukin-10, transforming growth factor-beta, and platelet-derived growth factor-alpha genes were constitutively expressed. Moreover, intragraft mRNA patterns of cytokines and growth factors between patients with GVD (n = 17) or without GVD (n = 17) were comparable. In contrast, during the first acute rejection episode a completely different pattern was found. Development of GVD was associated with IL-2 mRNA expression and not with the other cytokines analyzed. IL-2 mRNA was present in 77% of rejection EMB specimens obtained from patients with GVD versus 33% of the EMB specimens obtained from patients without GVD (p = 0.03) and not detectable in EMB specimens obtained from patients with no rejection. Also nonimmunologic risk factors such as longer ischemia time (median 193 vs 141 minutes; p = 0.002) and higher donor age (median 32 vs 23 years; p = 0.02) were associated with GVD. But no relation was found between these nonimmunologic risk factors and IL-2-positive acute rejections.

CONCLUSIONS

Nonspecific risk factors and IL-2-positive rejections may independently trigger GVD after clinical heart transplantation.

Blockade of the interleukin (IL)-2/IL-2 receptor pathway with a monoclonal anti-IL-2 receptor antibody (BT563) does not prevent the development of acute heart allograft rejection in humans

BACKGROUND

Anti-interleukin (IL)-2 receptor (IL-2R) antibodies have been used as rejection prophylaxis after organ transplantation. Despite this induction treatment, acute rejections may occur. We wondered whether these rejections developed via the IL-2/IL-2R pathway.

METHODS

In a prospective trial using BT563, a murine IgG1 anti-IL-2R antibody, for rejection prophylaxis after heart transplantation, 20 patients were treated in combination with cyclosporine from the day of transplantation (group A). As a control group, 31 patients were also treated with BT563, but in these patients, cyclosporine treatment was initiated on day 3 (group B).

RESULTS

Three patients from group A and two patients from group B died in the first postoperative month (of causes not related to acute rejection) and were left out of the analysis of rejection incidence. Freedom from acute rejection at 1 week after transplantation in group A (14/17; 82%) was lower than in group B (16/29; 55%), although the difference did not reach statistical significance. There was no difference in either the number of acute rejection episodes at 12 weeks or the required rejection treatments between groups A and B. Infectious complications were evenly distributed in both groups. Immunohistochemistry showed that during acute rejection, in the presence of circulating BT563, IL-2R-bearing cells were present in only one of five rejection biopsies (20%), whereas these cells were often present (6/8, or 75%) in rejections occurring in the absence of BT563. The presence of BT563 was associated with a similar difference in the mRNA expression of IL-2 (2/5 vs. 6/8).

CONCLUSIONS

Apparently, despite adequate blockade of the IL-2/IL-2R pathway, patients may develop acute rejection, reflecting the redundancy of the cytokine network. The ever-present IL-15 may well be a candidate for overtaking the role of IL-2.

Kinetics of IL-2 and IL-4 mRNA and protein production by graft-infiltrating lymphocytes responsible for rejection after clinical heart transplantation

During cardiac rejection we studied the kinetics of IL-2 and IL-4 mRNA and subsequent protein production by in vivo primed graft-infiltrating lymphocytes (GIL), using semiquantitative RT-PCR and ELISA. Following in vitro stimulation with either donor or third-party antigens, mRNA expression of IL-2 and IL-4 were already detectable 1-2 h after stimulation, while their protein production could be measured from 4 h onwards at least until 48 h. At both the mRNA and protein level, we measured a donor-specific signal for IL-2 and for IL-4 production (p = 0.02), while the relative donor-specific IL-2 mRNA level was significantly higher than the relative IL-4 mRNA level (p = 0.002). These observations suggest that after in vitro challenge with donor antigens, GIL obtained from rejecting cardiac allografts predominantly produce IL-2 mRNA and protein.

The intragraft cytokine mRNA pattern reflects the efficacy of steroid antirejection therapy

BACKGROUND

We studied the effect of antirejection therapy on intragraft cytokine mRNA expression.

METHODS

Therapy consisted of three doses of 1 gm of intravenous methylprednisolone. We determined its effect on intragraft mRNA expression of immunoregulatory (interleukin-2, interleukin-4) and inflammatory cytokines (interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha), and the high-affinity interleukin-2 receptor (p55 chain) in endomyocardial biopsy specimens from cardiac allograft recipients.

RESULTS

By reverse-transcriptase polymerase chain reaction methods, we detected mRNA transcription for interleukin-2 in 56% of the pretreatment endomyocardial biopsy specimens (n = 16), for interleukin-4 in 31%, and for interleukin-6 in 56% of the specimens, and interleukin-2 receptor, interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha were constitutively expressed. Individual cytokine mRNA profiles were not helpful in differentiating between rejections that proved to be methylprednisolone resistant (n = 9) or methylprednisolone sensitive (n = 7). After successful antirejection therapy, the overall intragraft mRNA expression was downregulated. None of the posttreatment endomyocardial biopsy specimens taken from six patients with methylprednisolone-sensitive rejections expressed the interleukin-2 gene, in contrast to 88% of the endomyocardial biopsy specimens obtained from eight patients with methylprednisolone-resistant rejections (p = 0.005). Moreover, intragraft interleukin-4 and interleukin-6 mRNA transcripts were hardly detectable (both 17%) in methylprednisolone-reversible rejections, but in ongoing rejections interleukin-4 mRNA expression was found in 62% (p = 0.14), and interleukin-6 was found in 88% of the endomyocardial biopsy specimens (p = 0.03). Semiquantitative analysis showed that the intragraft interleukin-2 receptor, interleukin-1 beta, and tumor necrosis factor-alpha mRNA levels were lower in posttreatment endomyocardial biopsy specimens from methylprednisolone-reversible rejections than in endomyocardial biopsy specimens from methylprednisolone-irreversible rejections (p = 0.03).

CONCLUSIONS

Our data suggest that the efficacy of antirejection therapy with methylprednisolone is reflected in intragraft cytokine mRNA profiles.

Intragraft IL-4 mRNA expression is associated with down-regulation of liver graft rejection

The mechanism underlying spontaneously resolving allograft rejection following clinical liver transplantation is unidentified. In this process, immunoregulatory T helper (Th)-2 cytokines like IL-4, often identified with down-regulation of the Th1-dependent (IL-2) cell-mediated response, might play a significant but unknown role. For this reason, we analyzed mRNA expression by reverse transcriptase-polymerase chain reaction (RT-PCR) in 57 biopsies derived from 19 recipients. Specimens included biopsies without evidence of rejection (n = 36), biopsies with histological evidence of rejection (n = 10) not followed by clinical signs of graft rejection, and biopsies with histological rejection that were accompanied with clinical rejection (n = 11), defined by rising serum bilirubin and aspartate amino transaminase (ASAT) levels. Intragraft IL-4 mRNA expression significantly correlated with spontaneously resolving rejections. In 70% (7/10) of these biopsies, IL-4 mRNA was detectable, while only 19% (7/36) of the biopsies without signs of rejection (p < 0.01; Fisher's exact test) and 18% (2/11) of the rejection biopsies concurrent with graft dysfunction expressed the IL-4 gene (p = 0.03). In contrast, IL-2 mRNA expression was not detectable in biopsies derived from the spontaneously resolving rejections. None (0/10) of these samples expressed the IL-2 gene, which was not significantly different from the proportion of biopsies transcribing the IL-2 gene in the absence of rejection (11%, 4/36). IL-2 mRNA expression was found more often in biopsies associated with graft dysfunction (36%, 4/11). These results show that IL-4, in contrast to IL-2 mRNA expression, is associated with spontaneously resolving liver rejection. This suggests that Th2 cells down-regulate the Th1-dependent cell-mediated immune response after clinical liver transplantation.

Patterns in donor-specific mRNA and protein production of Th1 and Th2 cytokines by graft-infiltrating lymphocytes and PBMC after heart transplantation

We used RT-PCR and ELISA to study the kinetics of IL-2 (Th1) and IL-4 (Th2) both on mRNA and protein level from "naive" PBMC and "primed" graft-infiltrating lymphocytes (GIL) obtained from a heart transplant recipient. For this purpose, these cells were stimulated for 1-48 h with donor and control third-party antigens. Only stimulation of GIL with donor-specific antigen resulted in early detectable IL-2 and IL-4 mRNA and protein levels. Maximal relative IL-2 mRNA levels were significantly higher than maximal relative IL-4 mRNA levels (100-fold) in both GIL and PBMC after donor-specific stimulation. This was accompanied by a maximum protein production of 908 pg/ml IL-2 and 19 pg/ml IL-4 by GIL, and of 82 pg/ml IL-2 and undetectable IL-4 production by PBMC. These results suggest that, after stimulation donor-specific "primed" GIL, and not "naive" PBMC, rapidly produce abundant levels of IL-2 (Th1) and IL-4 (Th2) at both the transcriptional and protein level.

Intragraft monitoring of rejection after prophylactic treatment with monoclonal anti-interleukin-2 receptor antibody (BT563) in heart transplant recipients

BACKGROUND

Anti-interleukin-2 receptor monoclonal antibodies have been used successfully in the prevention of rejection in cardiac allografts in several animal models.

METHODS

In an open randomized study murine monoclonal CD3 antibody and BT563, a murine anti-interleukin-2 receptor monoclonal antibody, were given as rejection prophylaxis during the first week after heart transplantation. Cyclosporine therapy was initiated at the third postoperative day.

RESULTS

In half the BT563-treated patients an early rejection was histologically shown at week 1, whereas heart transplant recipients treated with murine monoclonal CD3 antibody had a rejection incidence at week 1 of only 9%. During BT563 treatment CD25-positive cells (i.e., cells bearing the interleukin-2 receptor) were not detectable in peripheral blood. However, immunohistologic studies of endomyocardial biopsy specimens taken 1 week after transplantation showed the presence of CD25-positive cells within these specimens in 8 of 10 (80%) of patients with rejection. In patients without rejection CD25-positive cells were present in the biopsy specimens of only two of nine patients (22%). Reverse-transcriptase polymerase chain reaction studies on biopsy material showed the presence of messenger RNA for the interleukin-2 receptor in all and for interleukin-2 in three of five (60%) of biopsy specimens of rejecting grafts.

CONCLUSIONS

Although CD25-positive cells were not detectable in peripheral blood during BT563 treatment, these cells were at the same time found to be present within 80% of the endomyocardial biopsy specimens from the rejecting grafts. By initiating cyclosporine treatment at day 0, the synergistic effect of combining cyclosporine and anti-interleukin-2 receptor monoclonal antibodies may result in a lower rejection incidence.