Acute Renal Graft Rejection

Acute renal allograft rejection KW Wong

Acute renal allograft rejection - introduction

Renal transplantation is the treatment of choice for most patients with ESRD

Disparity between the supply of organs and the demand

About 20% of patients in US on waiting list are those with a failed graft

And 15% of performed transplantation are repeated transplantation

Acute rejection – defined as a sudden deterioration in renal allograft function as a result of the recipient’s immune response to the donor organ

A major risk factor for allograft failure

About 35% of allograft recipients have an episode of acute rejection in the first year

Acute rejection is associated with a 20% reduction in the one year survival rate of cadaveric grafts

Acute rejection is a strong risk factor for chronic rejection in recipients of renal grafts from cadaveric donors (Ferguson R Clin Transplant 1994;8:328-31)

The rate of acute rejection has dropped with the newer immunosuppressive combinations to between 10% and 25%

Loss of an allograft from acute rejection has also declined

Acute renal allograft rejection - DIAGNOSTIC POSSIBILITIES IN TRANSPLANT RELATED ACUTE RENAL FAILURE

1. Acute (cell-mediated) rejection

2. Delayed-appearing antibody-mediated rejection

3. Acute tubular necrosis

4. Cyclosporine or FK506 toxicity

5. Urine leak

6. Obstruction

7. Viral infection

8. Post-transplant lymphoproliferative disorder

9. Vascular thrombosis

10. Pre-renal azotemia

Acute renal allograft rejection- pathology

Two distinct immunopathological mechanisms responsible for acute rejection

Cell mediated immunity

Tubulointerstitial (70 – 85%)

Vascular

Antibody mediated (humoral) immunity

Vascular

C4d, without vascular involvement

Cell mediated – tubulointerstitial (70 – 85%)

Primary abnormalities – interstitium, diffusely oedematous and infiltrated by numerous leukocytes

Mainly mature and transformed lymphocytes, fewer monocytes and plasma cells

Occasionally eosinophils

Peritubular capillaries dilated and filled with lymphocytes

Characteristic feature – tubulitis (infiltration of tubular epithelium by lymphocytes) – lymphocytes and monocytes extend into the walls and lumina or tubules, w associated degenerative changes of epithelial cells

Cast matrix (Tamm-Horsfall protein) may be found in interstitium

Pathogenesis

Graft infiltration with T cells

Cytokines help recruit other cells such as macrophages and promote T-cell proliferation (tumor necrosis factor, interleukin 1,

interleukin 2, interferon )

The release of effector molecules granzyme and perforin via exocytosis leading to cell death

Risks for acute cellular rejection:

Delayed graft function

Retransplantation

Panel-reactive antibody 50%

Low immunosuppressive dosing

Poor compliance

African-American recipient

Cell mediated – vascular rejection

Lymphocytes, monocytes and foam cells undermine arterial endothelium

Endothelial cells – swollen and vacuolated

Often, but not always, occurs in concert with tubulointerstitial rejection

Acute transplant glomerulopathy – a form of glomerular cell-mediated rejection

Lymphocytes and monocytes accumulate in glomerular capillary lumina and mesangial regions

Immunofluorescence – discloses fibrin in interstitium

Segmental linear or granular IgM, C3 and fibrin found in glomerular capillary walls in acute transplant glomerulopathy

C4d staining is negative within peritubular capillaries

When treated successfully – interstitial inflammatory infiltrate diminishes rapidly, whereas oedema, tubular inflammation and tubular cell damage may persist for some time

Antibody-mediated - vascular

Vascular – uncommon, characterized by necrotizing arteritis with mural fibrinoid necrosis and variable inflammation (proliferation of inflammatory cells)

Endothelial cells severely damaged, luminal thrombosis common

Cortical infarction with focal interstitial haemorrhage

More severe lesion poorly responsive to therapy

Antibody-mediated – C4d positive

Diffuse peritubular capillary staining for complement component C4d

A split product of C4 in classical complement cascade

Described as a ‘footprint’ for the presence of humoral rejection

A marker for the complement activation associated with humoral rejection

Histologic appearance diverse – scattered glomerular, peritubular capillary and tubulointerstitial neutrophils

Only way to diagnose is with immunostaining for C4d

Should be performed on all biopsies obtained for renal transplant dysfunction

Acute renal allograft rejection- pathology C4d staining is seen in the peri-tubular capillaries

Acute Cellular Rejection: Interstitial

Clinical presentation

Time post-transplant:

Usually 7 to 30 days

If donor-specific transfusions have been given, may occur within the first week following transplant

may be seen weeks to years after transplant - medication compliance or environmental exposure (i. e, infection)

Accounts for 90% of early histologically proven rejection

‘ classic’ clinical picture of fever, oliguria, a tender, swollen graft – rarely seen

Most commonly asymptomatic modest rise in serum creatinine

Acute Cellular Rejection: Interstitial

Ultrasound:

Swollen kidney

Decreased echogenicity of the renal sinus, thickening of the uroepithelium

Prominent, hypoechoic medullary pyramids

Increased resistive index (peak systolic velocity—end diastolic velocity/peak systolic velocity)

Obstruction: ureteral tissue undergoing rejection

Renal scan:

Delayed and decreased blood flow

Decreased urine excretion

Acute Cellular Rejection: Vascular

Time post-transplant: Usually days to weeks

Symptoms: today usually no symptoms, but presentation may include fever, chills, night sweats, myalgias, tenderness over the allograft, decreased urine output

Pathogenesis

Antidonor, anti-HLA antibodies

Perhaps other antiendothelial antibodies

Risk factors for:

High panel-reactive antibody titer

Retransplantation

Antidonor antibodies before or developing after transplantation

Antibody-Mediated/Humoral Rejection

5% to 10% of rejection

Time post-transplant: hours to weeks

Acute accelerated oliguria if urine output has started or delayed graft function if urine output has not yet started

No symptoms or fever and allograft tenderness

More common in patients undergoing desensitization protocols for a positive cross-match against their living donor, i.e, preformed anti-donor antibodies

Antibody-Mediated/Humoral Rejection

Pathogenesis

Donor-specific immunoglobulin G (IgG) antibodies, presensitization against the donor

Anti-donor antibody deposition in the transplant

Activation of complement

Recruitment of polymorphonuclear cells and

lymphocytes

Acute renal allograft rejection –

European Best Practice Guidelines for Renal Transplantation (NDT 2000)

On diagnosis and treatment

Acute renal allograft rejection - European Best Practice Guidelines for Renal Transplantation (NDT 2000)

A

Acute rejection should be suspected in patients with established graft function who experience a rapid increase within 1 -2 days in their plasma creatinine conc. of >10-25% over baseline with or without decreased urine output, graft tenderness or fever in the absence of other obvious causes of acute graft dysfunction

The baseline plasma creatinine is the most recent creatinine conc. prior to the diagnosis of rejection.

(evidence level C)

Acute renal allograft rejection

the absolute increase in plasma creatinine conc. gave the best correlation with confirmed acute rejection

The percent change is more reliable in patients with a low muscle mass (children and older recipients, and patients with impaired function)

Recommended assessing changes of function as a % change from baseline over a period of 1 -2 days

Pre-CSA era – one or more clinical signs (fever, graft tenderness or decreased urine output)

In Efficacy Endpoints Database study – 54% confirmed acute rejection had no clinical signs

(Guttmann et al, proposed consensus for definitions and endpoints for clinical trials of acute kidney transplant rejection. Am J Kidney Dis 1998;31)

Risk factors for acute rejection

Retransplantation

Donor age >50 years

An organ from a female donor

Mismatches for broadly cross-reactive class I MHC antigens

HLA-DR mismatches

(Sijpkens YWJ, Paul LC et al)

B

It is recommended to exclude other causes of graft dysfunction and to take a biopsy to confirm the clinical diagnosis of acute rejection. The biopsy result can be used to guide the intensity of anti-rejection therapy or to assess the long-term prognosis

(evidence level B)

Causes of acute allograft dysfunction

• Acute rejection

• Vascular

• Obstruction

• Infection

• Drug toxicity

• Recurrent disease

• ATN (including delayed graft function)

Diagnosis of acute rejection

Clinical diagnosis

Biopsy – gold standard

Aspiration cytology

Non-invasive

– Urinary Perforin and Granzyme B

– sLewisx expression on PBL

– Urinary biometrics

Renal biopsy – gold standard

Advisable after exclusion of vascular and urological complications

Clinical prediction generally poor

Correct biopsy diagnosis predicted in only 43% (AJKD 1998; 31(suppl 1):S15-18)

In 19% of cases, unnecessary immuno-suppression was avoided

Rate of serious complications is low

In a study of >650 transplant biopsies – no death or graft loss (Hollander et al, JASN 1996; 7:1911)

Bleeding primary complication

1.1% required blood transfusion

0.4% embolisation of a bleeding kidney

Blood clots formed in bladder in 3%

Macroscopic haematuria 9%

Microscopic haematuria 64%

an adequate tissue sample as one that contains at least 10 glomeruli and two arteries

C

Reporting of biopsies should be standardized according to an internationally agreed scheme to reflect the histo-pathological pattern and severity of the rejection episode

(evidence level B)

Diagnostic Categories for Renal Allograft Biopsies ('97)

1. Normal

2. Antibody mediated rejection - Immediate (Hyperacute)/

Delayed (Accelerated Acute):

Polymorph accumulation in glomerular and peritubular capillaries with subsequent endothelial damage and capillary thrombosis

3. Borderline Changes: "Suspicious" for acute rejection

Grade "Suspicious" :This category is used when no intimal

arteritis is present, but there are foci of mild tubulitis (1 to 4

mononuclear cells/tubular cross section)

Mild interstitial mononuclear infiltrate involving less than 25% of the renal parenchyma

Diagnostic Categories for Renal Allograft Biopsies ('97)

4. Acute Cellular Rejection

Grade IA: Significant interstitial infiltration (>25% of parenchyma

affected) and foci of moderate tubulitis (> 4 mononuclear cells/tubular

cross section or group of 10 tubular cells)

Grade IB : Significant interstitial infiltration (> 25% of parenchyma

affected) and foci of severe tubulitis (> 10 mononuclear cells/tubular

cross section or group of 10 tubular cells)

Grade IIA : Cases with significant interstitial infiltration and mild to moderate intimal arteritis (v1)

Grade IIB: Severe intimal arteritis comprising > 25% of the lumenal area

(v2)

Grade III : “Transmural" arteritis or fibrinoid change and necrosis of

medial smooth muscle cells (v3 with lymphocytic inflammation)

Tubulitis, ie, infiltration of tubular epithelium by lymphocytes, is the hallmark of type I interstitial acute rejection. Different classifications have been put forth for diagnosis of acute rejection Type I

Moderate interstitial lymphoplasmacytic infiltrate is present with partial destruction of several tubules by infiltrating lymphocytes, ie, tubulitis. The extent of this process was sufficient to warrant a diagnosis of type I acute rejection Type I

There is intense, severe interstitial lymphoplasmacytic infiltrate that has nearly obliterated the underlying tubules. There is extensive tubulitis. Changes of this severity are not commonly seen in patients taking cyclosporine. When there is extensive, nodular, expansive lymphoplasmacytic infiltrate, atypia, and serpiginous necrosis, the alternative diagnosis of posttransplant lymphoproliferative disorder should be considered Type I

Acute vascular rejection is diagnosed by endothelialitis, ie, lymphocytes infiltrating under the endothelium. It often is present in conjunction with acute type I (interstitial) rejection, but may occur without concurrent interstitial rejection. It is thought that humoral mechanisms are pivotal in mediating vascular-type rejection. The biopsy shows minimal subendothelial lymphocytic infiltrate, diagnostic of type II vascular rejection

There is endothelial swelling and lymphocytic subendothelial infiltration in this medium size artery, indicative of endothelialitis (type II acute vascular rejection)

There is hyalinosis of the bottom interlobular artery and necrosis with subendothelial lymphocytic infiltrate in the top artery, indicative of type III acute vascular rejection

Antibody-mediated rejection has also been tightly linked with the presence of C4d staining in peritubular capillaries. C4d is a breakdown product of complement, and its presence in peritubular capillaries correlates strongly with the presence of anti-donor antibodies. This immunofluorescence test is thus used as an adjunct to suggest antibody-mediated mechanisms of acute rejection (anti-C4d immunofluorescence, x 400)

Prognostic value of diagnostic biopsy

Short term prognosis – with current immunosuppressive drug regimens, graft loss due to acute rejection rare, biopsies unlikely to indicate short term prognosis

Intermediate term – histo-pathological pattern of acute rejection correlates with later graft loss

Interstitial rejection have better prognosis than predominantly vascular rejections

Amount of macrophages/plasma cells also assoc. with impaired intermediate outcome

D

in patients with prolonged delayed graft function, surveillance biopsies should be considered to detect or exclude acute rejection episodes

(evidence level B)

Some centres perform weekly surveillance biopsies in patients with DGF, until graft recovers

As DGF associated with increased acute rejection risk, and most acute rejection episodes lack constitutional symptoms

Subclinical rejection episodes

Surveillance/protocol biopsy first 6 months

Intermediate cellular infiltration observed in a third (JASN 1999; 10:1582-9)

in patients with unimpaired renal function – importance of such infiltrate unknown

in 72% of cases – borderline lesions in biopsies taken due to elevated creatinine – do no evolve into acute rejection episodes within 40 days if left untreated (JASN 1999;10:1806-14)

Anti rejection therapy results in an improvement in renal function in only small fraction of patients

Increasing baseline maintenance immunosuppression fails to suppress these subclinical rejections (JASN 1999; 10:1801-05)

Treatment with corticosteroids results in a significant decerase in early and late acute rejection episodes, a reduced chronic tubulointerstitial score at 6 months and a lower serum creatinine at 24 months (JASN 1998; 9:2129-34)

Acute renal allograft rejection - treatment

Three components

A short period of intense immuno-suppresion

Prophylaxis against opportunistic infections

Modification of maintenance immunosuppression

Acute renal allograft rejection – treatment - European Best Practice Guidelines for Renal Transplantation (NDT 2000)

Guidelines

A. for the treatment of the first acute cellular rejection episode, high doses of intravenous methylprednisolone are recommended. This treatment is expected to reverse most acute rejection episodes. Although the use of polyclonal (ATG/ALG) or monoclonal (OKT3) antibodies as first-line therapy is effective, their adverse event profile and cost mean that the use of corticosteroids as first-line therapy is preferred. (evidence level C)

TREATMENT OF REJECTION

Acute Cellular

Steroids

● Variable doses depending on the transplant program, often 250 to 1,000 mg/d intravenously for 3 to 5 days; oral administration can also be used at lower doses (up to about 250 mg/d).

● Histologic/clinical response within 6 days.

● Response rate 60% to 75%, more for early rejections.

Corticosteroid – the most commonly used primary treatment for acute rejection episodes

250, 500 or 1000mg bolus doses of methylprednisolone iv for 2 – 4 days

Successful responses –

Recipients without fever (72 vs 61%)

Less than a Banff grade III rejection (92 vs 75%)

Acute renal allograft rejection – treatment

Use of polyclonal or monoclonal antibody as first line – rejection reversal from 67 to 98% of cases

Most centers use antibody therapy for

Severe acute rejection (Banff IIB or III)

Second rejection episodes

Steroid resistant rejections

B. ATG/ALG or OKT3 are recommended for the treatment of severe acute rejection episodes (Banff grade III), recurrent acute rejection episodes, corticosteroid resistant rejection episodes or in patients with contra-indications to corticosteroids. (evidence level C)

Antilymphocyte antibodies

● OKT3: mouse, anti-CD3 receptor antibody, 5 mg/d for 7 to 14 days:

Monitor CD3 counts to determine anti–T cell effect

If OKT3 has been given before, check anti-mouse antibody level prior to administration to determine probability of clinically relevant inhibitory levels

Reverses over 90% of early and up to 70% of late acute rejection

● Thymoglobulin: polyclonal anti–T-cell antibody, 1.5 mg/kg for 7 to 14 doses, may follow T-cell subsets to help dosing.

● Lymphocyte immune globulin/antithymocyte globulin (Atgam): polyclonal T-cell antibody, 10 to 15 mg/kg for 7 to 14 doses.

Assessment of therapy outcome

A successful response to therapy as a relative serum creatinine concentration value that is <110% of the day 0 (or rejection) creatinine level, and returns to the day 0 creatinine level or lower during the first 5 days of therapy

Proposed Consensus for Definitions and Endpoints for Clinical Trials of Acute Kidney Transplant Rejection

Ronald D. Guttmann et.al (American Journal of Kidney Diseases,Vol 31, No 6, Suppl 1 (June), 1998: pp S40-S46)

steroid resistant rejection – an acute rejection episode that has been treated only with 250 – 1000mg methylprednisolone and where the serum creatinine conc. increases as early as day 3 of therapy, and continue to rise unless treated with a different anti rejection therapy

Qualification of steroid resistant – a clinical assessment, not to rely on biopsy

C. in patients with recurrent rejection after anti-T lymphocyte antibody treatment, it is recommended to modify baseline immunosuppression. (evidence level B)

One study on refractory rejection while on CsA maintenance treatment – CsA discontinued and replaced tacrolimus

Graft function improved in 78%

Stabilized in 11%

Progressive deterioration in 11% (related to the pre-conversion serum creatinine)

Protocol biopsies after one week of tacrolimus therapy – no rejection in 60%, histological improvement in 13%, no change in 20%, and worsening in 7%

Adverse events – neurological – tremor, headache and insomnia; diarhhoea, nausea, and abdominal pain, hyperkalaemia and nephrotoxicity

A multicenter trial of FK506 therapy in refractory acute renal allograft rejection – a report of the tacrolimus kidney transplantation rescue study group (Transplantation 1996; :594-599)

Another study on persistent rejection within 28 days of receiving at least 7 days of anti-t lymphocyte antibodies

Assigned to MMF (3g/day) + CsA+ steroid, or to high doses of methylpred iv for 5 days + aza + CsA and steroid

Treatment with MMF – 45% reduction in graft loss and death by 6 months, reduction in biopsy proven rejection episode or treatment failure by almost 50%

The Mycophenolate Mofetil Renal Refractory Rejection Study Group (Clin Transplant 1996; 10:131-135)

Both tacrolimus and MMF equally effective in patients with refractory rejection

Tacrolimus produced a lower recurrent rejection rate, associated with less use of anti-lymphocyte antibodies to treat recurrent rejections, less serious adverse events and CMV disease

Meta-analysis of FK506 and MMF refractory rejection trials in renal transplantation (Transplant Proc 1998; 30:1297-98)

Antibody-mediated acute rejection

Immediate outcome uniformly worse than those of acute cellular rejection

Often steroid and anti-lymphocyte antibody therapy resistant

Graft loss is frequent (29 – 75%)

Treatment not well defined

Plasma exchange

One uncontrolled open study (only 5 patients) – PE used with switching CsA and Aza to tacrolimus and MMF

All grafts rescued

Decreased donor-specific antibodies

Improved graft function

Pascual et al. Transplantation 1998; 66: 1460-1464

D. ALG/ATG is preferable to OKT3 for the treatment of acute rejection episodes. Although both preparations are effective in reversing such episodes, OKT3 has a slightly poorer adverse profile because of the first-dose effect. (evidence level B)

There is consensus that the use of OKT3 is associated with more side effects, esp those related to cytokine release syndrome

E. rabbit anti-T lymphocyte antisera are preferable to horse anti-T lymphocyte antisera. (evidence level A)

A multicentre, double-blind, randomized trial

Patients with proven acute rejection received 7-14 dyas of treatment with either a rabbit ATG, or a horse ATG

Rabbit ATG had –

better rejection reversal rate (88 vs 76%)

Less frequent recurrent rejection at 90 days after therapy (17 vs 36%)

Graft survival, incidence of adverse events and post-therapy infection no difference

Gaber et al Transplantation 1998; 66: 29-37

Post intensive immunosuppression – continuing or restarting prophylaxis against CMV should part of protocol

Association between CMV infection/disease and acute rejection

McLaughlin et al. Transplantation vol 74; 6: 813-816, Sep 2002

Pouteil-Noble et al, CMV infection: an etiological factor for rejection?. Transplantation 1993;55: 851

one study also showed – valacyclovir for CMV prophylaxis reduced risk of acute rejection

Transplantation vol 79;3: 317-324 Feb 2005

European Best Practice Guidelines – on CMV infection

F. during the first year post transplant, all CMV positive recipients, treated with polyclonal or monoclonal antibodies either as induction therapy or for an acute steroid resistant rejection, should receive CMV prophylaxis

Evidence level B

G. prophylaxis must be selected from the following five different validated modalities of preventive treatment for CMV infection/disease

i. weekly intravenous infusion of hyperimmune globulins for 6 weeks (high dose) or 16 weeks (lower dose)

ii. Oral acyclovir administered for 12 weeks at a daily dose of 3200mg adjusted regularly to GFR

iii. Oral valacyclovir given for 90 days at a daily dose of 8000mg adjusted regularly to GFR

iv. Gancyclovir administered for at least 14 days at a daily dose of 10mg/kg adjusted regularly to GFR

v. oral gancyclovir given for a longer period (2 to 12 weeks) at a daily dose of 3000mg adjusted regularly to GFR

Evidence level A

J. acute rejection episodes are clearly associated with CMV infection/disease. In this situation, CMV infection should be treated first using iv gancyclovir as recommended and, only when necessary, acute rejection may be treated by methylprednisolone pulses. ATG/ALG/OKT3 should be avoided whenever possible. (evidence level C)

conclusions

Rejection should be diagnosed by biopsy only

Rejection usually indicates insufficient immunosuppression – should prompt an increase of immunosuppression

Pulse steroid administration remains as first line and efficacious in two-thirds of cases

Steroid resistant rejections, particularly of the dangerous vascular type, can be treated with various regimes administration of ATG, addition of MMF, switching form CsA to tacrolimus

Patient’s view of the situation and his or her individual perspective are key factors in the assessment

NON STANDARD TREATMENT

Intravenous IgG (IVIgG)

Not conventional treatment, dosing schedules not firmly established

Jordan et al reported IVIg able to reverse vascular rejection in a series of 10 patients with various transplants (Transplantation 66:800-805, 1998)

Luke and Scantlebury et al – reported their experience in treating 17 patients with IVIG to reverse steroid- or antilymphocyte antibody resistant rejection – patient and graft survival (94 and 71%), reversal/reduction in severity of rejection in 82% (Transplantation Vol 72, 419-422, August 2001)

IVIgG: 2 g/kg over 18 hours up to a maximum dose of 140 g, repeat dose if needed in 30 days

NONSTANDARD TREATMENT – in desperate cases

Radiation

Radiation therapy for renal transplant rejection refractory to pulse steroids and OKT3 (Noyes et al) - 72 consecutive patients with kidney graft rejection were treated with local irradiation to the transplanted renal graft following failure of medical management. All patients received pulse steroids and OKT3, an anti-CD3 immunosuppressant. Patients who failed to respond to methylprednisolone and OKT3 therapy were referred for radiation therapy. The median time from the diagnosis of rejection to irradiation was 8 days. All kidney grafts received local graft irradiation to a total of 8 Gy delivered in four daily fractions

RESULTS: Sixty (83%) patients initially responded to radiotherapy at 7 days after completion of radiotherapy, as defined by a decrease in serum creatinine. Thirty-five responding patients have not experienced a second episode of graft rejection. Overall, 43 (60%) patients have renal graft survival, with a median follow-up of 16 months (range of 6-73 months

CONCLUSION: It is concluded that there is a subgroup of kidney graft patients undergoing graft rejection who are refractory to pulse steroids and OKT3 therapy where irradiation may be an effective modality with high rates of response and a moderate rate of graft survival. However, a prospective, randomized trial in these medically refractory patients is needed to ascertain whether these results are clinically significant

NONSTANDARD TREATMENT

Rituximab – anti CD20 antibody

Inhibit B cell proliferation, induce cellular apoptosis

Case series by Yolanda et al – 27 patients confirmed rejection, not responded to steroid/ATG/pheresis – received a single dose of rituximab, 3 patients graft loss, 24 patients successfully treated with reduction of serum creatinine