Practical Applications in Immunohistochemistry: Evaluation of Rejection and Infection in Organ Transplantation

Guidelines on antibody use in physiology research

Antibodies are one of the most used reagents in scientific laboratories and are critical components for a multitude of experiments in physiology research. Over the past decade, concerns about many biological methods, including those that use antibodies, have arisen as several laboratories were unable to reproduce the scientific data obtained in other laboratories. The lack of reproducibility could be largely attributed to inadequate reporting of detailed methods, no or limited verification by authors, and the production and use of unvalidated antibodies. The goal of this guideline article is to review best practices concerning commonly used techniques involving antibodies, including immunoblotting, immunohistochemistry, and flow cytometry. Awareness and integration of best practices will increase the rigor and reproducibility of these techniques and elevate the quality of physiology research.

Complement testing in the clinical laboratory

The complement system is the human's first line of defense against microbial pathogens because of its important housekeeping and infection/inflammation roles. It is composed of a series of soluble and cell-bound proteins that are activated in a cascade effect, similar to the coagulation pathways. There are different pattern recognizing molecules that activate the complement system in response to stimuli or threats, acting through three initiation pathways: classical, lectin, and alternative. All three activation pathways converge at the C3 component and share the terminal pathway. The main outputs of the complement system action are lytic killing of microbes, the release of pro-inflammatory anaphylatoxins, and opsonization of targets. Laboratory testing is relevant in the setting of suspected complement deficiencies, as well as in the emerging number of diseases related to dysregulation (over-activation) of complement. Most common assays measure complement lytic activity and the different complement component concentrations. Specialized testing includes the evaluation of autoantibodies against complement components, activation fragments, and genetic studies. In this review, we cover laboratory testing for complement and the conditions with complement involvement, as well as current challenges in the field.

High levels of dd-cfDNA identify patients with TCMR 1A and borderline allograft rejection at elevated risk of graft injury

The clinical importance of subclinical, early T cell-mediated rejection (Banff TCMR 1A and borderline lesions) remains unclear, due, in part to the fact that histologic lesions used to characterize early TCMR can be nonspecific. Donor-derived cell-free DNA (dd-cfDNA) is an important molecular marker of active graft injury. Over a study period from June 2017 to May 2019, we assessed clinical outcomes in 79 patients diagnosed with TCMR 1A/borderline rejection across 11 US centers with a simultaneous measurement of dd-cfDNA. Forty-two patients had elevated dd-cfDNA (≥0.5%) and 37 patients had low levels (<0.5%). Elevated levels of dd-cfDNA predicted adverse clinical outcomes: among patients with elevated cfDNA, estimated glomerular filtration rate declined by 8.5% (interquartile rate [IQR] -16.22% to -1.39%) (-3.50 mL/min/1.73 m2 IQR -8.00 to -1.00) vs 0% (-4.92%, 4.76%) in low dd-cfDNA patients (P = .004), de novo donor-specific antibody formation was seen in 40% (17/42) vs 2.7% (P < .0001), and future or persistent rejection occurred in 9 of 42 patients (21.4%) vs 0% (P = .003). The use of dd-cfDNA may complement the Banff classification and to risk stratify patients with borderline/TCMR 1A identified on biopsy.

The impact of C4d testing on tissue adequacy in lung transplant surveillance

BACKGROUND

Surveillance transbronchial biopsies are routinely used to assess lung allograft rejection. While the criteria for diagnosing acute cellular rejection have been well-established, the morphological findings associated with antibody mediated rejection are variable. To increase the sensitivity for antibody mediated rejection, a portion of a biopsy can be used for C4d immunofluorescence testing, along with histologic findings and donor specific antibodies. When the number of alveolar pieces in a biopsy is small, the relative utility of sending one piece for C4d testing is unclear.

METHODS

Pathology reports of 1400 surveillance transbronchial lung biopsies from 2008 to 2017 were reviewed to obtain the number of pieces of alveolar parenchyma in each case. Based on a standard definition of adequacy as five pieces of well-expanded alveolar parenchyma, reports with five fragments were grouped as "adequate", four pieces as a "marginal" sample, and three or less were considered an "inadequate" sample.

RESULTS

Of the 1400 biopsies, 653 specimens had 5 or more pieces of alveolar parenchyma.747 specimens were submitted with less than 5 pieces and 290 of those were considered marginal. In all marginal cases, a piece was withheld for C4d immunofluorescence testing.

CONCLUSIONS

About 21% of specimens would have the recommended 5 pieces of alveolar parenchyma if not for the withholding of pieces for C4d IF testing. Over the span of 10 years, 290 such cases were recorded at our institution. Given this nontrivial impact, it is unclear if C4d immunofluorescence testing should be performed on surveillance transbronchial biopsies when the number of pieces in the specimen is marginal.

Neuropathological Findings in Susac Syndrome: An Autopsy Report

A 24-year-old woman developed encephalopathy, branch retinal artery occlusion, hearing loss, and had "snowball" lesions in the corpus callosum, classic findings of Susac syndrome (SuS). Despite intensive immunosuppressive therapy, she lapsed into a coma, and died 7 months after the onset of her illness. Neuropathological examination, revealed perivascular inflammation and vasculitis involving small vessels, associated with vascular narrowing and occlusion, and numerous microinfarcts diffusely throughout the brain. The findings establish SuS as a neuroinflammatory condition that can include vasculitis. This represents the most comprehensive report of the neuropathological findings in SuS.

Stoma formation after lymphoproliferative disorders and immunosuppression therapy

Post-transplant lymphoproliferative disorders (PTLD) are lymphomas that may arise in organ, bone marrow or stem cell transplant recipients who are taking immunosuppressive drugs to prevent rejection of the transplant. The likelihood of developing PTLD depends on the type of transplant. PTLD is a potentially severe complication of post-transplant treatment, with an uncertain prognosis. Lymphoproliferative disorders can also occur in people taking immunosuppressants for inflammatory bowel disease. This article will explore PTLD and discuss the experience of caring for patients who developed lymphoproliferative conditions and required emergency stoma formation. The emotional and physical impact of surgery upon these patients, who have already experienced a protracted treatment journey, will be explored. Implications for practice for the lymphoma team and stoma nurse specialists involved with the care of these patients will also be considered.

Practical Guidance for Clinical Microbiology Laboratories: Viruses Causing Acute Respiratory Tract Infections

Respiratory viral infections are associated with a wide range of acute syndromes and infectious disease processes in children and adults worldwide. Many viruses are implicated in these infections, and these viruses are spread largely via respiratory means between humans but also occasionally from animals to humans. This article is an American Society for Microbiology (ASM)-sponsored Practical Guidance for Clinical Microbiology (PGCM) document identifying best practices for diagnosis and characterization of viruses that cause acute respiratory infections and replaces the most recent prior version of the ASM-sponsored Cumitech 21 document, Laboratory Diagnosis of Viral Respiratory Disease, published in 1986. The scope of the original document was quite broad, with an emphasis on clinical diagnosis of a wide variety of infectious agents and laboratory focus on antigen detection and viral culture. The new PGCM document is designed to be used by laboratorians in a wide variety of diagnostic and public health microbiology/virology laboratory settings worldwide. The article provides guidance to a rapidly changing field of diagnostics and outlines the epidemiology and clinical impact of acute respiratory viral infections, including preferred methods of specimen collection and current methods for diagnosis and characterization of viral pathogens causing acute respiratory tract infections. Compared to the case in 1986, molecular techniques are now the preferred diagnostic approaches for the detection of acute respiratory viruses, and they allow for automation, high-throughput workflows, and near-patient testing. These changes require quality assurance programs to prevent laboratory contamination as well as strong preanalytical screening approaches to utilize laboratory resources appropriately. Appropriate guidance from laboratorians to stakeholders will allow for appropriate specimen collection, as well as correct test ordering that will quickly identify highly transmissible emerging pathogens.

Brincidofovir as Salvage Therapy for Adenovirus Disease in Intestinal Transplant Recipients

BACKGROUND

Adenoviruses are double-stranded DNA viruses that typically cause mild self-limiting respiratory, ocular, and gastrointestinal infections. In immunocompromised patients, especially transplant recipients, the infection can be severe, with dissemination and multiorgan failure. In intestinal transplant recipients, the incidence is as high as 57%. To our knowledge, no standardized guidelines or U.S. Food and Drug Administration-approved medications exist for the treatment of adenovirus disease.

AIMS

We describe two isolated intestinal transplant recipients who developed adenovirus disease (viremia with viral enteritis) that was managed with a new experimental drug, brincidofovir (an oral lipid conjugate prodrug of cidofovir), as salvage therapy.

RESULTS

The first patient was a 44-year-old woman who developed adenoviral enteritis 1 month after transplantation, which resolved with ribavirin therapy. Two weeks later, the infection recurred, and brincidofovir was initiated. While receiving this therapy for 3 months, she developed severe acute rejection, which was managed with rabbit antithymocyte globulin followed by infliximab. Eventually, complete resolution of the rejection and adenoviral enteritis was achieved. At 12 months posttransplantation, the patient was healthy and tolerating enteral feeding. The second patient was a 28-year-old man who had undergone isolated intestinal transplantation 6 years before he presented with generalized weakness and an increased ostomy output; he was diagnosed with adenoviral enteritis. Maintenance immunosuppression was reduced, and brincidofovir was started. The infection resolved with a month of therapy. Six months after the infection, he was healthy and tolerating enteral feeding.

CONCLUSION

This is the first publication, to our knowledge, to describe two cases in which brincidofovir was used to successfully treat adenovirus infection in intestinal transplant recipients. Thus, these cases demonstrate that brincidofovir appears to be a safe and effective option in the management of adenoviral enteritis in these patients.

Guidelines for authors and reviewers on antibody use in physiology studies

Antibody use is a critical component of cardiovascular physiology research, and antibodies are used to monitor protein abundance (immunoblot analysis) and protein expression and localization (in tissue by immunohistochemistry and in cells by immunocytochemistry). With ongoing discussions on how to improve reproducibility and rigor, the goal of this review is to provide best practice guidelines regarding how to optimize antibody use for increased rigor and reproducibility in both immunoblot analysis and immunohistochemistry approaches.

Listen to this article’s corresponding podcast at http://ajpheart.podbean.com/e/guidelines-on-antibody-use-in-physiology-studies/.

Pathology of Lung Rejection: Cellular and Humoral Mediated

Acute rejection is an important risk factor for bronchiolitis obliterans syndrome, the clinical manifestation of chronic airway rejection in lung allograft recipients. Patients with acute rejection might be asymptomatic or present with symptoms that are not specific and can be also seen in other conditions. Clinical tests such as pulmonary function tests and imaging studies among others usually are abnormal; however, their results are also not specific for acute rejection. Histopathologic features of acute rejection in adequate samples of transbronchial lung biopsy of the lung allograft are currently the gold standard to assess for acute rejection in lung transplant recipients. Acute alloreactive injury can affect both the vasculature and the airways. Currently, the guidelines of the 2007 International Society of Heart and Lung Transplantation consensus conference are recommended for the histopathologic assessment of rejection. There are no specific morphologic features recognized to diagnose antibody-mediated rejection (AMR) in lung allografts. Therefore, the diagnosis of AMR currently requires a “triple test” including clinical features, serologic evidence of donor-specific antibodies, and pathologic findings supportive of AMR. Complement 4d deposition is used to support a diagnosis of AMR in many solid organ transplants; however, its significance for the diagnosis of AMR in lung allografts is not entirely clear. This chapter discusses the currently recommended guidelines for the assessment of cellular rejection of lung allografts and summarizes our knowledge about morphologic features and immunophenotypic tests that might help in the diagnosis of AMR.

Common issues in the management of patients in the waiting list and after liver transplantation

The present document contains the recommendations of an expert panel of transplant hepatologists, appointed by the Italian Association for the Study of the Liver (AISF), on how to manage the most common aspects of liver transplantation: the topics covered include: new treatments for HCV in patients on the waiting list for liver transplantation; antiviral treatments in patients with HCV recurrence after liver transplantation; prophylaxis for HBV recurrence after liver transplantation; indications for liver transplantation in alcoholic liver disease; and Immunosuppressive therapy. The statements on each topic were approved by participants at the AISF Transplant Hepatologist Expert Meeting (organized by the Permanent Committee on Liver Transplantation in Mondello on 4-5 October 2015), and are graded according to the Oxford classification of levels of evidence.

Diagnosis of Acute Cellular Rejection and Antibody-Mediated Rejection on Lung Transplant Biopsies: A Perspective From Members of the Pulmonary Pathology Society

Context.—

The diagnosis and grading of acute cellular and antibody-mediated rejection (AMR) in lung allograft biopsies is important because rejection can lead to acute graft dysfunction and/or failure and may contribute to chronic graft failure. While acute cellular rejection is well defined histologically, no reproducible specific features of AMR are currently identified. Therefore, a combination of clinical features, serology, histopathology, and immunologic findings is suggested for the diagnosis of AMR.

Objective.—

To describe the perspective of members of the Pulmonary Pathology Society (PPS) on the workup of lung allograft transbronchial biopsy and the diagnosis of acute cellular rejection and AMR in lung transplant.

Data Sources.—

Reports by the International Society for Heart and Lung Transplantation (ISHLT), experience of members of PPS who routinely review lung allograft biopsies, and search of literature database (PubMed).

Conclusions.—

Acute cellular rejection should be assessed and graded according to the 2007 working formulation of the ISHLT. As currently no specific features are known for AMR in lung allografts, the triple test (clinical allograft dysfunction, donor-specific antibodies, pathologic findings) should be used for its diagnosis. C4d staining might be performed when morphologic, clinical, and/or serologic features suggestive of AMR are identified.