AMR in Liver Transplantation:

Note on DSA

• Presence of DSA associated with increased risk of

• Chronic rejection

• Acute rejection with ductopenia

• Unexplained graft fibrosis

• Unexplained biliary complications

• De-novo AIH (non-HLA DSA)

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AMR in Liver Transplantation:

Note on DSA • Differences in class I vs class II DSA

• Liver allograft in simultaneous liver-kidney transplant was thought to

provide protection from DSA and decrease risk of kidney AMR, but high

MFI HLA Class II DSA still at risk

• Likely higher MFI cut-off values than in other SOT

• DSA IgG subclass may be important

• IgG3 strongly associated with graft loss

• DSA found in control patients with no other signs, symptoms,

or risk factors

AMR in Liver Transplantation: Role of C4d

In studies that do include the full

clinicopathologic correlation and clear

diagnostic terms:

• Diffuse clearly positive C4d staining in >50% of

portal tracts (IHC) or sinusoids (IF)

• Correlates with presence of DSA

• Correlates with histologic features of AMR

• Prevalence of reported cases of liver AMR meeting

criteria of other solid-organ systems: 0.6-3.7%

AMR in Liver Transplantation:

Role of C4d

• Take Home Message

• Utility of looking for C4d not clearly established

• No consensus diagnosis of AMR which includes C4d

• IHC: small portal vessel staining is most specific

• IF: sinusoidal staining is most specific

• C4d staining may be seen in other conditions

• Banff 2011 liver group goal for 2013:

• Better understanding of spectrum of AMR and consensus

guidelines for C4d interpretation

AMR in Liver Transplantation: Differential

Diagnosis • Hyperacute rejection

• Since not often biopsied, histologic features are

derived from failed explanted allografts and are

not specific

• Severe preservation-reperfusion injury

• Graft ischemia

• Idiopathic massive hemorrhagic graft necrosis

AMR in Liver Transplantation: Differential

Diagnosis

•Acute antibody mediated rejection – Biliary obstruction/technical biliary complications

• Histologic features overlap:

– Bile ductular reaction

– Portal tract neutrophils

– Cholestasis

– Preservation-reperfusion injury

– Acute cellular rejection

– Infection/Sepsis

– Cholestasis

– Acute ascending cholangitis

– Ischemic injury

Take Home Message: AMR dx • Due nonspecificity of histologic findings, AMR

should only be suggested as an etiology of the

findings

• Definitive diagnosis requires supportive

clinical/serologic features and exclusion of the

histologic mimics

AMR in Liver Transplantation: Pitfalls

• The four major diagnostic criteria for AMR dx in renal and

cardiac allografts have not been adopted for liver

– Clinical graft dysfunction

– Compatible histologic features

– Deposition of C4d

– Serologic evidence of DSA

• No routine testing for DSA in liver recipients

• C4d immunostaining is less established/less reliable

AMR in Liver Transplantation: Clinical

Aspects

• Prophylaxis

• For ABO-incompatible grafts (living donor)

• B-cell directed immunosuppression • Rituximab, IVIg, Plasma exchange, Splenectomy

• Treatment

• B-cell directed immunosuppression

• Bortezomib: proteasome inhibitor, depletes

plasma cells→ decreased Ab production

Townsend: Sabiston Textbook of Surgery, 18th ed.

Copyright © 2007 Saunders, An Imprint of Elsevier

AMR in Intestinal Transplantation: Background

AMR in Intestinal Transplantation: Clinical

Aspects

• Extremely limited literature

• More common in patients undergoing retransplantation

after failed graft/chronic rejection

• DSA alone associated with worse outcome

• DSA with histologic ACR – consider concurrent AMR

• High PRA is a risk factor for rejection

• DSA can persist asymptomatically after hyperacute

rejection resolves

AMR in Intestinal Transplantation: Clinical

Aspects

• Presentation

• First 2 weeks post-transplant

• Increased stoma output

• ACR poorly responsive to standard therapy

• Persistent mucosal

ischemia/congestion/hemorrhage • Peri- and post-operative syndrome

AMR in Intestinal Transplantation: Clinical

Aspects

Peri- and post-operative syndrome

• Patients with strong crossmatch (T-cell cytotoxicity test) and

high PRA

• Segmental graft spasm, cyanosis, petechial hemorrhage

at reperfusion, lasting 45m

• Blood-tinged ostomy content within a few hours

• Ileostomy mucosal congestion for 1-2weeks

• Endoscopically, graft mucosa dusky with congestion,

hemorrhagic

Wu et al. Human Pathology, 2004 Nov;35(11):1332-9.

Wu et al. Human Pathology, 2004 Nov;35(11):1332-9.

AMR in Intestinal Transplantation:

Background

• Hyperacute rejection (hours)

• Disseminated thrombosis

• Total ischemic necrosis

• Associated with presensitization

• high PRA, DSA

• Prophylaxis – desensitization

• IVIg to reduce PRA

• Protocols not standardized

AMR in Intestinal Transplantation:

Histologic Features

• Capillary endothelial cell enlargement

• Fibrin thrombi

• Vascular congestion

• Hemorrhage

• Neutrophil margination

• Ulceration

• Crypt apoptosis +/-

AMR in Intestinal Transplantation:

Histologic Features

• Features of ACR may be present

• Crypt apoptosis

• Crypt epithelial injury

• Lamina propria mononuclear inflammatory

infiltrate

• Ulceration +/-

• Architectural distortion +/-

• Severe ACR with arteritis

Remotti et al. Arch Pathol Lab Med, 2012 Jul;136

Crypt apoptosis

Crypt injury & dropout

Denudation

AMR in Intestinal Transplantation: Role of

C4d

• Nonspecific: • C4d + in 36% of intestinal allografts with rejection

• And in 27% without rejection

• May be positive in small arterioles of normal intestine

Troxell et al. Arch Pathol Lab Med, 2006 130:1489-96.

AMR in Intestinal Transplantation: Role of

C4d

• Take Home message • C4d deposition is nonspecific and may be present independent of

rejection or absent during hyperacute rejection

AMR in Intestinal Transplantation:

Differential Diagnosis

• Vascular insufficiency/thrombosis

• Ischemic change

• Preservation/Reperfusion injury

• First few days post-op, resolves within 1 week

• Ischemic change, regenerative epithelium, villous

blunting, minimal inflammation

• Prior biopsy site

AMR in Intestinal Transplantation:

Differential Diagnosis

• Chronic rejection

• Arteriopathy: Mesenteric, serosal, and submucosal

vessels

• Luminal narrowing associated with intimal and medial

hyperplasia

• Associated mucosal changes

• Mucin loss, submucosal fibrosis

• Also paneth cell loss, neural hyperplasia

• Nonspecific changes: crypt apoptosis and dropout, villous

blunting, lamina propria fibrosis

AMR in Intestinal Transplantation: Chronic

rejection

Does AMR have a role in chronic rejection?

• Intestinal allograft explants

• Contracted mesentery with fibrosis and chronic

arteriopathy

• Sampling mesenteric vessels for AMR before

this stage is technically not feasible

AMR in Intestinal Transplantation:

Diagnosis Take Home message

• Suspect AMR with DSA, histologic evidence of

vascular alteration, and early/severe/resistant

clinical signs of rejection

• Treating a suspicion since no way to confirm

AMR dx

AMR in Intestinal Transplantation: Clinical

Aspects

• Treatment

• OKT3

• Steroids

• Prostaglandin E

• Prognosis

• May not be associated with chronic rejection

• Does not contribute to overall mortality or graft loss

AMR in Pancreas Transplantation

• Pancreas allograft infrequently biopsied due to perceived

risk

• AMR does occur in pancreas allograft

• Diagnosis requires 3 components (Banff 2011):

• Histology

• C4d IHC

• DSA

• (Clinical graft dysfunction not required)

3/3 = acute AMR

2/3 = consistent with acute AMR

1/3 = clinical exclusion of AMR required

Acute AMR in Pancreas Transplantation

• Histology: evidence of tissue injury

• Inflammation of interacinar capillaries (capillaritis)

• Acinar cell damage (swelling, necrosis, apoptosis,

dropout)

• Vasculitis

• Thrombosis

• C4d positive:

• Diffuse C4d staining of interacinar capillaries (≥ 5% of

acinar lobule surface

Chronic Active AMR in Pancreas

Transplantation Diagnosis requires:

• Combined features of AMR and chronic allograft

rejection/graft fibrosis

• Fibrotic expansion of fibrous septae; exocrine atrophy

• Exclusion of features of acute T-cell-mediated

rejection

• Acinar inflammation→damage; also inflammation of

septae, ducts, venules

Summary • Liver

• AMR can be suggested as dx, as histologic features overlap with other dx

• C4d utility not clearly established

• No consensus diagnostic criteria

• Small bowel • Histologic features and clinical syndrome described

• C4d nonspecific

• Pancreas • Consensus dx criteria including histology, C4d IHC, and

DSA

• Infrequently biopsied

Summary

• Kidney

• AMR very significant, acute and chronic forms, C4d done routinely

(IF preferred)

• Heart

• About 15% of patients, markedly increased risk of chronic rejection

and death, C4d very helpful, IHC or IF

• Lung

• Rare, diagnosis based on clinical graft dysfunction, circulating

antibodies, absence of cellular rejection, non-specific C4d staining

common, however strong endothelial staining reported

References • Hübscher SG. Antibody-mediated rejection in the liver allograft. Curr Opin Organ Transplant. 2012

Jun;17(3):280-6.

• Fayek SA. The value of C4d deposit in post liver transplant liver biopsies. Transpl Immunol. 2012 Dec;27(4):166-70.

• Ratner LE, Phelan D, Brunt EM, Mohanakumar T, Hanto DW. Probable antibody-mediated failure of two sequential ABO-compatible hepatic allografts in a single recipient. Transplantation. 1993 Apr;55(4):814-9.

• Musat AI, Agni RM, Wai PY, Pirsch JD, Lorentzen DF, Powell A, Leverson GE, Bellingham JM, Fernandez LA, Foley DP, Mezrich JD, D'Alessandro AM, Lucey MR. The significance of donor-specific HLA antibodies in rejection and ductopenia development in ABO compatible liver transplantation. Am J Transplant. 2011 Mar;11(3):500-10.

• Mengel M, Sis B, Haas M, Colvin RB, Halloran PF, Racusen LC, Solez K, Cendales L, Demetris AJ, Drachenberg CB, Farver CF, Rodriguez ER, Wallace WD, Glotz D; Banff meeting report writing committee. Banff 2011 Meeting report: new concepts in antibody-mediated rejection. Am J Transplant. 2012 Mar;12(3):563-70.

• Dick AA, Horslen S. Antibody-mediated rejection after intestinal transplantation. Curr Opin Organ Transplant. 2012 Jun;17(3):250-7.

• de Kort H, Roufosse C, Bajema IM, Drachenberg CB. Pancreas transplantation, antibodies and rejection: where do we stand? Curr Opin Organ Transplant. 2013 Jun;18(3):337-44.

• Wu T, Abu-Elmagd K, Bond G, Demetris AJ. A clinicopathologic study of isolated intestinal allografts with preformed IgG lymphocytotoxic antibodies. Hum Pathol. 2004 Nov;35(11):1332-9.

• Swanson BJ, Talmon GA, Wisecarver JW, Grant WJ, Radio SJ. Histologic analysis of chronic rejection in

small bowel transplantation: mucosal and vascular alterations. Transplantation. 2013 Jan 27;95(2):378-82.