In 1990, an international grading scheme for the grading of pulmonary allograft rejection was adopted by the International Society for Heart and Lung Transplantation (ISHLT) and was modified in 1995 by an expanded group of pathologists. The original and revised classifications have served the lung transplant community well, facilitating communication between transplant centers with regard to both patient management and research. In 2006, under the direction of the ISHLT, a multi-disciplinary review of the biopsy grading system was undertaken to update the scheme, address inconsistencies of use, and consider the current knowledge of antibody-mediated rejection in the lung. This article summarizes the revised consensus classification of lung allograft rejection. In brief, acute rejection is based on perivascular and interstitial mononuclear infiltrates, Grade A0 (none), Grade A1 (minimal), Grade A2 (mild), Grade A3 (moderate) and Grade A4 (severe), as previously. The revised (R) categories of small airways inflammation, lymphocytic bronchiolitis, are as follows: Grade B0 (none), Grade B1R (low grade, 1996, B1 and B2), Grade B2R (high grade, 1996, B3 and B4) and BX (ungradeable). Chronic rejection, obliterative bronchiolitis (Grade C), is described as present (C1) or absent (C0), without reference to presence of inflammatory activity. Chronic vascular rejection is unchanged as Grade D. Recommendations are made for the evaluation of antibody-mediated rejection, recognizing that this is a controversial entity in the lung, less well developed and understood than in other solid-organ grafts, and with no consensus reached on diagnostic features. Differential diagnoses of acute rejection, airway inflammation and chronic rejection are described and technical considerations revisited. This consensus revision of the working formulation was approved by the ISHLT board of directors in April 2007.

Revision of the 1990 Working Formulation for the Standardization of Nomenclature in the Diagnosis of Heart Rejection

https://onlinelibrary.wiley.com/doi/pdf/10.1034/j.1600-6143.2003.00072.x

Antibody-mediated rejection criteria - an addition to the Banff 97 classification of renal allograft rejection.

Recent studies show that alloantibodies mediate a substantial proportion of graft-rejection episodes, contributing to both early and late graft loss. Rejection that is caused by antibody is mediated by different mechanisms from rejection that is caused by T cells, thereby requiring other approaches to treatment and prevention. Antibody induces rejection acutely through the fixation of complement, resulting in tissue injury and coagulation. In addition, complement activation recruits macrophages and neutrophils, causing additional endothelial injury. Antibody and complement also induce gene expression by endothelial cells, which is thought to remodel arteries and basement membranes, leading to fixed and irreversible anatomical lesions that permanently compromise graft function.

Antibody-mediated organ-allograft rejection

During the last 25 years, antibody-mediated rejection of the cardiac allograft has evolved from a relatively obscure concept to a recognized clinical complication in the management of heart transplant patients. Herein we report the consensus findings from a series of meetings held between 2010-2012 to develop a Working Formulation for the pathologic diagnosis, grading, and reporting of cardiac antibody-mediated rejection. The diagnostic criteria for its morphologic and immunopathologic components are enumerated, illustrated, and described in detail. Numerous challenges and unresolved clinical, immunologic, and pathologic questions remain to which a Working Formulation may facilitate answers.

The 2013 International Society for Heart and Lung Transplantation Working Formulation for the standardization of nomenclature in the pathologic diagnosis of antibody-mediated rejection in heart transplantation

2011 Consensus statement on endomyocardial biopsy from the Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology

We prospectively studied 551 sequential endomyocardial biopsies from 36 consecutive cardiac allografts. With the use of a combination of light microscopy (including careful evaluation of vascular changes) and immunofluorescence to detect the deposition of immunoglobulin and complement, we identified three patterns of allograft rejection, designated as cellular rejection, vascular (humoral) rejection, and mixed rejection. Cellular rejection was diagnosed with modified Billingham criteria. Vascular rejection was diagnosed by finding the combination of prominent endothelial cell swelling and/or vasculitis on light microscopy and the vascular deposition of immunoglobulin and complement by immunofluorescence. In such patients, cellular lymphoid infiltrates were uniformly absent at the time the vascular changes were detected. Mixed rejection consisted of findings of both cellular and vascular rejection occurring simultaneously. Twenty of 36 allografts exhibited cellular rejection; seven allografts showed vascular rejection, and nine allografts developed mixed rejection. The vascular (humoral) pattern of rejection was important to identify because the patients with this type of rejection had a significantly decreased survival compared with that of patients with cellular rejection (p less than 0.05). Survival in the mixed rejection category was intermediate. Positive donor-specific cross-match and/or panel-reactive antibody greater than or equal to 5% and systolic dysfunction were seen in three of the seven allografts with vascular (humoral) rejection but not in the other types. In the early period after transplant (up to 3 weeks after transplant), the only reliable identifying characteristics of patients with vascular (humoral) rejection were the presence of vascular immunoglobulin and complement assessed by immunofluorescence and endothelial cell swelling and interstitial edema as confirmed by histologic examination. We conclude that immunofluorescence should be routinely done on all heart biopsies for the first month after transplantation. Patients with vascular (humoral) rejection cannot be reliably identified by any other means.

Nunoda S

Papers

Vascular (humoral) rejection in heart transplantation: pathologic observations and clinical implications.