C4d Staining Research Articles

The Revised (2013) Banff Classification for Antibody-Mediated Rejection of Renal Allografts: Update, Difficulties, and Future Considerations.

The Banff 2013 classification (Banff 2013) for antibody-mediated rejection (ABMR) in renal allografts represents the first major revision of the original Banff classification for ABMR that was published in 2003. The main impetus for this revision was the need to include C4d-negative ABMR, although this revised classification contains a number of additional features based on findings reported from 2007 to 2013. Since its publication, several studies have examined the validity of different aspects of Banff 2013 and compared it to earlier (2003, 2007) versions of the Banff ABMR classification. Recent evidence, albeit limited, indicates that Banff 2013 represents an improvement over the previous versions, enhancing our ability to accurately diagnose cases of acute/active and chronic active ABMR on renal allograft biopsy. Molecular studies appear to justify the threshold value of glomerulitis plus peritubular capillaritis score ≥2 required by Banff 2013 for the diagnosis of C4d-negative ABMR; however, other aspects of the classification, including its overall interobserver reproducibility, the clinical significance of the category of C4d staining without evidence of rejection, and whether surrogate markers might potentially substitute for the requirement for the presence of donor-specific antibodies, require additional investigation.

Diagnostic value of immunohistochemical staining for C3d and C4d in paraffin sections in bullous pemphigoid

Objective To estimate the value of immunohistochemical staining for C3d and C4d in paraffin-embedded tissue sections for the auxiliary diagnosis of bullous pemphigoid (BP). Methods Paraffin-embedded tissue sections from 20 patients with BP served as the experiment group, and those from lesions of 9 patients with familial benign pemphigus and 4 patients with epidermolysis bullosa as well as from normal skin served as the controls. Immunohistochemical SP method was used to measure the expressions of C3d and C4d in these paraffin sections. Results The deposition of C3d and C4d was observed in the basement membrane at the dermo-epidermal junction in 95% (19/20) of BP tissue sections, but undetected in any of the familial benign pemphigus or epidermolysis bullosa tissue sections. Conclusion Immunohistochemical staining for C3d and C4d in paraffin-embedded tissue sections may serve as an auxiliary method for the diagnosis of BP. Key words: Pemphigoid, bullous; Paraffin embedding; Microtomy; Immunohistochemistry; Complement C3d; Complement C4d

Acute Cellular Rejection and C4d Positivity in Heart Transplantation : A Manifestation of Asymptomatic Antibody-Mediated Rejection?

The role of routine C4d staining in endomyocardial biopsy specimens is uncertain. The implications of a diagnosis of acute cellular rejection (ACR) with a positive C4d with or without any evidence of antibody-mediated rejection (AMR) are unclear. This study sought to evaluate a distinct phenotype of ACR+/C4d+ in AMR- patients. Data on C4d, ACR, and AMR were collected. Donor-specific antibody (DSA), panel-reactive antibody (PRA), flow crossmatch, and data on ACR and AMR episodes were also reviewed. Thirty-five patients were followed. Group I with C4d+ biopsy specimens was compared with group II with C4d- biopsy specimens. ACR greater than 1R was higher in group I compared with group II (50% vs 7.4%; P = .01). Clinical suspicion of AMR, positive retrospective crossmatches, and detection of de novo DSA were also higher in group I. Our result indicate that C4d and ACR positivity in posttransplant patients may be a harbinger of a subclinical form of asymptomatic AMR.

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

-Immunohistochemical analysis of tissue biopsy specimens is a crucial tool in diagnosis of both rejection and infection in patients with solid organ transplants. In the past 15 years, the concept of antibody-mediated rejection has been refined, and diagnostic criteria have been codified in renal, heart, pancreas, and lung allografts (with studies ongoing in liver, small intestine, and composite grafts), all of which include immunoanalysis for the complement split product C4d. -To review the general concepts of C4d biology and immunoanalysis, followed by organ-allograft-specific data, and interpretative nuances for kidney, pancreas, and heart, with discussion of early literature for lung and liver biopsies. Additionally, practical applications and limitations of immunostains for infectious organisms (Polyomavirus, Adenoviridae [adenovirus], and the herpes virus family, including Herpes simplex virus, Cytomegalovirus, Human herpes virus 8, and Epstein-Barr virus) are reviewed in the context of transplant recipients. -Our experience and published primary and review literature. -Immunohistochemistry continues to have an important role in transplant pathology, most notably C4d staining in assessment of antibody-mediated rejection and assessment of viral pathogens in tissue. In all facets of transplant pathology, correlation of morphology with special studies and clinical data is critical, as is close communication with the transplant team.

Immune Complex Mediated Glomerulonephritis with Acute Thrombotic Microangiopathy following Newly Detected Hepatitis B Virus Infection in a Kidney Transplant Recipient.

Hepatitis B virus (HBV) presents a risk to patients and staff in renal units. To minimise viral transmission, there are international and UK guidelines recommending HBV immunisation for patients commencing renal replacement therapy (RRT) and HBV surveillance in kidney transplant recipients. We report the case of a 56-year-old male who was immunised against HBV before starting haemodialysis. He received a deceased donor kidney transplant three years later, at which time there was no evidence of HBV infection. After a further six years he developed an acute kidney injury; allograft biopsy revealed an acute thrombotic microangiopathy (TMA) with glomerulitis, peritubular capillaritis, and C4d staining. Due to a “full house” immunoprofile, tests including virological screening were undertaken, which revealed acute HBV infection. Entecavir treatment resulted in an improvement in viral load and kidney function. HBV genotyping demonstrated a vaccine escape mutant, suggesting “past resolved” infection that reactivated with immunosuppression, though posttransplant acquisition cannot be excluded. This is the first reported case of acute HBV infection associated with immune complex mediated glomerulonephritis and TMA. Furthermore, it highlights the importance of HBV surveillance in kidney transplant recipients, which although addressed by UK guidelines is not currently practiced in all UK units.

Prevalence of erythrocytopenia & thrombocytopenia in Eastern Indian population & its correlation with acute antibody mediated renal transplant rejection & cytomegaloviral nephropathy

Objective: Our objective was to study the prevalence of thrombocytopenia & erythrocytopenia post renal transplantation in Eastern Indian population. Thrombocytopenia & erythrocytopenia are common phenomena prevailing post transplant rejection. It is found to occur in patients developing HCMV (human cytomegaloviral nephropathy), post transplantation. Whereas in the case of none rejected patients thrombocytopenia is unlikely to occur. Methods: Several methodologies such as the serological cross match, HLA-cross match DSA luminex, renal biopsy including C4d staining, hematological RBC & platelet count monitoring were adopted in the study, along with these the serum creatinine levels of the rejected patients were tested by making use of several biochemical approaches. Statistical analysis of the data obtained from the laboratories, were also done by the software prism 4.1. Results: Out of total population of 30 patients selected randomly, 24 were found to have successful transplants as for them a significant increase in both platelet & RBC count were noticed post transplantation where as for the other 6 patients a significant decrease in the RBC & platelet count was observed post transplantation along with a significant increase in the serum creatinine levels. There was also a significant decrease in the GFR (glomerular filtration rate) which was an indication of some sort of graft dysfunctioning. All the patients were checked for viral nephropathy & the above 6 patients were found to develop HCMV nephropathy. For the above mentioned 6 patients, the presence of C4d marker in their renal peritubular capillaries after performing the immunehistochemical C4d staining was a key indicator of acute antibody mediated rejection. Conclusion: Our study clearly reveals that Thrombocytopenia & erythrocytopenia was quite common in the patients with acute antibody mediated renal transplant rejection. A low RBC & platelet count persisted in them even after transplantation owing to allograft rejection, & HCMV nephropathy. Whereas for the patients with successful transplants events such as thrombocytopenia & erythrocytopenia were nevertheless unlikely.

Diagnosing Lymphocytic Myocarditis in Adult Autopsies Combining the Dallas Criteria with Immunohistochemical Stainings

Aim: Endomyocardial biopsies form the golden standard in diagnosing (borderline) lymphocytic myocarditis ((B)- LM) in living patients. Herein immunohistochemistry(IH) is mandatory. Diagnosing (B)-LM in autopsy hearts however is less defined. In this study we performed immunohistochemical stainings of heart slides in a cohort of consecutive adult autopsies that were evaluated subsequently with the Dallas criteria. Methods: Sections of the myocardium of consecutive adult autopsies (n=107) performed at Symbiant, Pathology Expert Centre, from January 1, 2012, to December 31, 2012 were revised. The two Hematoxylin/Eosin (H&E) slides of the heart with the highest number of interstitial inflammatory cells were stained for LCA (leukocyte common antigen) and activated complement (C3d). The slides were then analysed for clusters (≥1) of LCA-positive lymphocytes, with or without cardiomyocyte adhesion. C3d staining was used to visualize myocytolysis. Results: In H&E slides only, LM was found in 2 out of 107 cases (1.9%), but no B-LM was diagnosed. Using IH and applying the Dallas criteria, LM was found in 4 cases (3.7%) and B-LM in 4 additional cases (3.7%) out of 107. Conclusions: Combining the Dallas criteria with immunohistochemical stainings, LCA (identifying lymphocytes) and C3d (visualizing myocytolysis), improves the diagnosis of (B)-LM in autopsy hearts.

Presentation and Outcomes of C4d-Negative Antibody-Mediated Rejection After Kidney Transplantation

The updated Banff classification allows for the diagnosis of antibody-mediated rejection (AMR) in the absence of peritubular capillary C4d staining. Our objective was to quantify allograft loss risk in patients with consistently C4d-negative AMR (n = 51) compared with C4d-positive AMR patients (n = 156) and matched control subjects without AMR. All first-year posttransplant biopsy results from January 2004 through June 2014 were reviewed and correlated with the presence of donor-specific antibody (DSA). C4d-negative AMR patients were not different from C4d-positive AMR patients on any baseline characteristics, including immunologic risk factors (panel reactive antibody, prior transplant, HLA mismatch, donor type, DSA class, and anti-HLA/ABO-incompatibility). C4d-positive AMR patients were significantly more likely to have a clinical presentation (85.3% vs. 54.9%, p < 0.001), and those patients presented substantially earlier posttransplantation (median 14 [interquartile range 8-32] days vs. 46 [interquartile range 20-191], p < 0.001) and were three times more common (7.8% vs 2.5%). One- and 2-year post-AMR-defining biopsy graft survival in C4d-negative AMR patients was 93.4% and 90.2% versus 86.8% and 82.6% in C4d-positive AMR patients, respectively (p = 0.4). C4d-negative AMR was associated with a 2.56-fold (95% confidence interval, 1.08-6.05, p = 0.033) increased risk of graft loss compared with AMR-free matched controls. No clinical characteristics were identified that reliably distinguished C4d-negative from C4d-positive AMR. However, both phenotypes are associated with increased graft loss and thus warrant consideration for intervention.

Evaluation of Renal Allograft Biopsies for Graft Dysfunction and Relevance of C4d Staining in Antibody Mediated Rejection.

Biopsy remains gold standard for diagnosis of Graft Dysfunction (GD). It guides clinical management, provides valuable insights into pathogenesis of early and late allograft injury and is indispensable for distinguishing rejection from non- rejection causes of GD. The primary aim of the study was to evaluate the diverse histomorphological lesions in renal allograft biopsy (RAB). Further, we determined the frequency of peritubular capillary (PTC) C4d positivity and its correlation with microvascular inflammation in Antibody Mediated Rejection (AMR). This was a prospective study on RAB over a period of 2 months. Histopathological evaluation was undertaken as per revised Banff'13 schema. Immunohistochemistry was performed to detect PTC C4d deposition. Sixty five diagnostic biopsies were evaluated. Mean patient age was 34 years and males were predominant. The time interval between graft biopsy and transplantation ranged from 5 days to 8 years, with 52.3% biopsies belonging to period of ≤ 6 months post-transplant. Immune injuries were observed in 40 biopsies out of which AMR was observed in 35 biopsies. Calcineurin inhibitor toxicity (CNI Toxicity) was the second commonest cause observed in 12 biopsies and other lesions including de novo glomerulopathies were observed in the remaining biopsies. The sensitivity of C4d in detecting acute AMR was 55% and chronic AMR was 23.5. AMR and CNI Toxicity account for majority of graft dysfunction. C4d is not as sensitive a marker of AMR, as was initially thought. Higher proportion of moderate microvascular inflammation is found in diffuse C4d positive cases compared to focal C4d positive cases.

Development and validation of a prognostic index for allograft outcome in kidney recipients with transplant glomerulopathy

We studied 92 patients with transplant glomerulopathy to develop a prognostic index based on the risk factors for allograft failure within five years of diagnosis (Development cohort). During 60 months (median) follow up, 64 patients developed allograft failure. A chronic-inflammation score generated by combining Banff ci, ct and ti scores, serum creatinine and proteinuria at biopsy, were independent risk factors for allograft failure. Based on the Cox model, we developed a prognostic index and classified patients into risk groups. Compared to the low risk group (median allograft survival over 60 months from diagnosis), patients in the medium risk group had a hazard ratio of 2.83 (median survival 25 months), while those in the high risk group had a hazard ratio of 5.96 (median survival 3.7 months). We next evaluated the performance of the prognostic index in an independent external cohort of 47 patients with transplant glomerulopathy (Validation cohort). The hazard ratios were 2.18 (median survival 19 months) and 16.27 (median survival 1.6 months), respectively, for patients in the medium and high risk groups, compared to the low risk group (median survival 47 months). Our prognostic index model did well in measures of discrimination and calibration. Thus, risk stratification of transplant glomerulopathy based on our prognostic index may provide informative insight for both the patient and physician regarding prognosis and treatment.

Increased complement C4d deposition at the maternal-fetal interface in unexplained recurrent miscarriage

C4d is a footprint of antibody-mediated classical complement activation, and has evolved as a useful diagnostic marker of antibody-mediated rejection. It is unknown if complement activation, as reflected by C4d deposition plays a role in unexplained recurrent miscarriage.In a case-control study products of conception of 35 women with three or more unexplained consecutive miscarriages within 20 weeks of gestation with the same partner (case group), 22 women with one spontaneous sporadic miscarriage and no history of complicated pregnancy(ies) (control group 1), and 40 women who underwent an elective abortion for psychosocial reasons (control group 2) were included. Immunohistochemical staining for C4d was performed on products of conception. Positivity for C4d was scored semi-quantitatively.C4d deposition was present in products of conception of 14 out of 35 women with unexplained recurrent miscarriage (40.0%), compared to 6 out of 22 women with a sporadic miscarriage (27.3%), and 4 out of 40 women with an elective abortion (10.0%) (p=0.020).C4d is increased at the maternal-fetal interface in women with unexplained recurrent miscarriage, which may reflect an aberrant anti-fetal immunity in these women. Further knowledge of the specific pathogenic mechanism may lead to the development of new treatment strategies for this group of women.

Correlation of Circulating Complement-Fixing Donor-Specific Antibodies Identified by the C1q Assay and Presence of C4d in Endomyocardial Biopsy Specimens.

Donor-specific antibodies (DSAs) are associated with increased cardiac graft loss. We applied a C1q solid-phase assay in parallel with the standard immunoglobulin G (IgG) single antigen bead (SAB) assay to examine the correlation of circulating complement-fixing donor-specific antibodies and the presence of C4d in endomyocardial biopsy (EMB) specimens. We retrospectively studied the relationship of C1q+ DSAs and C4d immunofluorescence (IF) in 49 EMB specimens from 44 heart transplant recipients who had concurrent EMB, C4d IF, and DSA measurements. We applied a C1q SAB in parallel with the standard IgG SAB assay to examine the DSA profiles in heart transplant patients posttransplant. A better concordance is observed between C1q+ DSAs with C4d IF+ compared with IgG DSAs with C4d IF + (40% vs 24%, P = .02). However, the correlation of C1q DSAs with C4d IF is not statistically significant (P = .24). Importantly, C1q+ DSAs were observed in 16 of 17 cases with C4d IF+; 24 cases had circulating C1q+ DSAs without detectable C4d staining, suggesting that that the presence of C1q+ DSAs may precede the detection of C4d deposition in EMB specimens and/or the development of antibody-mediated rejection. In this cohort of 44 patients, no significant correlation was observed between circulating C1q DSAs and C4d IF in EMB specimens. Additional studies are needed to further evaluate the association of C1q DSAs with EMB specimens and C4d staining.

The Banff Conferences on renal allograft pathology – the latest 2013 report

The Banff Conference diagnostic categories and their criteria for renal biopsy interpretation were created in 1991 by a group comprising nephrologists, pathologists, transplant surgeons and immunologists. These guidelines are widely used in many countries. Every two years, participants at these meetings present and discuss research findings that have added to our knowledge of allograft pathology. From the start, features of T-cell mediated rejection were established. This was followed by discovery of C4d staining in biopsy tissue and better characterisation of antibody mediated rejection. The formation of working groups to look into problematic areas has allowed better refinements to be made to the classification scheme. The latest Banff 2013 report is significant for the inclusion of a C4d-negative category under humoral rejection. Together with the realisation that endarteritis may be antibody mediated, this latest report will greatly impact how pathologists interpret the allograft biopsy.

De novo donor-specific anti-HLA antibodies mediated rejection in liver-transplant patients.

The incidence and consequences of de novo donor-specific anti-HLA antibodies (DSAs) after liver transplantation (LT) are not well known. We investigated the incidence, risk factors, and complications associated with de novo DSAs in this setting. A total of 152 de novo liver-transplant patients, without preformed anti-HLA DSAs, were tested for anti-HLA antibodies, with single-antigen bead technology, before, at transplantation, at 1, 3, 6 and 12months after transplantation, and thereafter annually and at each time they presented with increased liver-enzyme levels until the last follow-up, that is, 34 (1.5-77) months. Twenty-one patients (14%) developed de novo DSAs. Of these, five patients had C1q-binding DSAs (24%). Younger age, low exposure to calcineurin inhibitors, and noncompliance were predictive factors for de novo DSA formation. Nine of the 21 patients (43%) with de novo DSAs experienced an acute antibody-mediated rejection (AMR). Positive C4d staining was more frequently observed in liver biopsies of patients with AMR (9/9 vs. 1/12, P<0.0001). Eight patients received a B-cell targeting therapy, and one patient received polyclonal antibodies. Only one patient required retransplantation. Patient- and graft-survival rates did not differ between patients with and without DSAs. In conclusion, liver-transplant patients with liver abnormalities should be screened for DSAs and AMR.

AJKD Atlas of Renal Pathology: Chronic Antibody-Mediated Rejection

Chronic antibody-mediated rejection is commonly associated with progressive loss of kidney function and proteinuria, although early stages may be subclinical and recognizable only through protocol biopsies. Diagnostic criteria according to the Banff 2013 classification (Haas et al, Am J Transplant 2014:14(2):272-283) include the presence of all of the following:1.Histologic evidence of chronic tissue injury, defined by the presence of at least one of the following:a.Transplant glomerulopathy (cg > 0) in the absence of chronic thrombotic microangiopathyb.Severe peritubular capillary basement membrane multilayering by electron microscopyc.New-onset arterial intimal fibrosis with no other known etiology2.Current/recent histologic evidence of antibody interaction with vascular endothelium, defined by the presence of at least one of the following:a.Linear C4d staining in peritubular capillaries (at least 10% by immunofluorescence [IF] on frozen sections or any positivity by immunohistochemistry on paraffin sections)b.At least moderate microvascular inflammation (g + ptc > 2)c.Increased expression of tissue gene transcripts indicative of endothelial injury3.Presence of donor-specific antibodies (DSA; HLA or non-HLA) in the serum Similar to acute antibody-mediated rejection, endothelial injury results from interaction between DSA with primarily mismatched HLA or non-HLA molecules. Repetitive and chronic endothelial damage is associated with new basement membrane formation, which in glomeruli manifests as glomerular basement membrane duplication (transplant glomerulopathy), often with resulting segmental sclerosis, and multilayering of the peritubular capillary basement membrane. Podocyte injury and foot process effacement are common findings. Glomerular basement membrane duplication is also found in other conditions associated with chronic endothelial damage, causing a membranoproliferative pattern of injury. Chronic thrombotic microangiopathy may be indistinguishable from transplant glomerulopathy on a morphologic basis unless features of concomitant acute thrombotic microangiopathy or vascular changes are present. In such cases, correlation with clinical history will be important. Membranoproliferative glomerulonephritis due to immune complex processes (lupus nephritis, immunoglobulin A nephropathy, cryoglobulinemic glomerulonephritis, etc) must be ruled out by IF and electron microscopy. Peritubular capillary basement membrane multilayering, especially if not severe (<7 layers), is not specific to chronic antibody-mediated rejection. Arterial intimal fibrosis is a common finding, often associated with chronic hypertension and aging. Scattered T cells and foam cells may be present in the expanded intima, but are not specific for chronic antibody-mediated rejection and may also be seen in chronic T-cell–mediated rejection. •Transplant glomerulopathy•Peritubular capillary basement membrane multilayering•Peritubular capillary C4d stainingFigure 2Transplant glomerulopathy with prominent glomerular basement membrane duplication and cellular interposition in a capillary loop. Podocytes show significant foot process effacement (electron microscopy).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3Chronic antibody-mediated rejection with severe peritubular capillary multilayering (>7 layers of basement membrane), representing response to repetitive and chronic endothelial injury. Note that the endothelial cell is swollen and has lost its normal fenestrations (electron microscopy).View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 4Chronic antibody-mediated rejection with diffuse linear C4d staining in peritubular capillaries (immunofluorescence microscopy, C4d).View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Nodular Arteriolar Hyalinosis as Histopathologic Hallmark of Calcineurin Inhibitor Nephrotoxicity: Does It Always Have the Same Meaning?

IntroductionNodular arteriolar hyalinosis (NAH) is a typical, although not specific, histological finding of calcineurin inhibitor toxicity (CNIT). The objective of our study was to assess the reason why some patients showing strong NAH in renal graft biopsies who underwent calcineurin inhibitor (CNI) withdrawal presented very poor outcome whereas others improved graft function. Material and MethodsWe performed 207 renal graft biopsies between January 2011 and May 2014 due to clinical criteria. In 13 patients CNI withdrawal was performed, and the major histopathological finding was severe NAH. The results after this action were analyzed. ResultsWe selected 2 groups: good outcome and poor outcome. Eight patients showed good results including stabilization or improvement of graft function. Five patients presented poor results requiring chronic hemodialysis. C4d staining was negative in all biopsy specimens, and peritubular capillaritis was not observed. To identify potential prognostic markers we retrospectively reviewed biopsy samples looking for minor or nonspecific features, especially inflammation scores both global and on fibrotic areas as per Banff classification. Mean serum creatinine level at time of biopsy and mean arteriolar hyalinosis score did not show significant differences between both groups. In contrast, the poor results group presented a higher mean global inflammation score compared with the good results patients. ConclusionsNAH is not a risk factor for poor renal graft outcome by itself. Other histopathologic findings, usually considered as secondary markers, like the inflammation score, should be considered before deciding CNI withdrawal.

Antibody-mediated rejection.

Pulmonary antibody-mediated rejection (AMR) while contributing to acute and chronic allograft dysfunction remains a diagnostic and therapeutic challenge. The diagnostic tenets upon which AMR is defined will be reviewed in the light of recent studies. The introduction of solid phase assays such as the Luminex platform has provided a wealth of quantitative data on the presence of anti-human leukocyte antigen (HLA) donor-specific antibodies (DSA). Further studies are required to better define the relationship of circulating DSA and activation of proinflammatory immune pathways that result in allograft dysfunction. The limitations of C4d staining in defining AMR are highlighted from recent studies in lung transplantation and from the 2013 Banff meeting on renal transplantation. The current challenge to the lung transplant community is to agree on a working definition of pulmonary AMR. Only then can we better appreciate the epidemiology, clinical phenotypes, and treatment of AMR.

Plasma Cell–Rich Rejection After Kidney Transplantation and the Role of Donor-Specific Antibodies: A Case Report and Review of the Literature

ObjectiveWe report a case of the clinical course and pathologic findings for a kidney transplant recipient with plasma cell–rich rejection (PCRR) accompanied by antibody-mediated rejection (ABMR). MethodsA 29-year-old man with end-stage renal disease caused by lupus nephritis received an ABO-compatible living kidney transplant. ResultsEighteen months after transplantation, the patient presented with proteinuria and increased serum creatinine. An episode biopsy revealed severe tubulointerstitial infiltration with plasma cells accompanied by peritubular capillaritis and positive findings on immunofluorescent C4d staining. Donor-specific antibodies were positive for DR52, and the patient was subsequently diagnosed with PCRR accompanied by ABMR. Treatment was initiated with high-dose steroids, intravenous immunoglobulin, gusperimus hydrochloride, muronmonab antibody CD3, and rituximab. However, ABMR persisted and allograft failure developed 20 months after onset. ConclusionsWe argue that PCRR accompanied by ABMR is a subtype of PCRR that can progress to allograft failure owing to persistent ABMR.

Significance of C4d Immunostaining in Placental Chronic Intervillositis

Deposition of the complement split product C4d is a phenomenon studied extensively as a marker for complement activation in antibody-mediated transplant rejection. C4d also is observed in placental disease processes including spontaneous abortion, infarct, and villitis of unknown origins. Massive chronic intervillositis is a rare placental abnormality associated with increased risk of growth restriction, fetal death, and recurrent fetal loss. In this study, we evaluated C4d immunostaining in placentas with accumulation of intervillous monocytes with and without villitis. Archived placentas from Kosair Children's Hospital (Louisville, KY) and Seattle Children's Hospital (Seattle, WA) were selected and divided into 4 groups, 16 cases of intervillositis with complicated pregnancy, 15 cases of uncomplicated intervillositis, 20 cases of complicated villitis, and 13 cases of uncomplicated villitis, all with varying degrees of monocytic cells in the intervillous space. Representative specimen blocks were immunohistochemically stained for C4d. The percentage of positive staining of the microvillous surface of the syncytiotrophoblast was scored by five pathologists, and the following consensus score was determined: 0 = 0% to 5%; 1 = 5% to 25%; 2 = 25% to 75%; and 3 ≥ 75%. C4d immunostain localized to the microvillous border of syncytiotrophoblast in many of the placentas. C4d staining was more strongly associated with intervillositis than with villitis (odds ratio: 6.3; confidence interval: 2.1-18.7; P = 0.001).

Plasmapheresis, Photopheresis, and Endovenous Immunoglobulin in Acute Antibody-mediated Rejection in Kidney Transplantation

IntroductionAcute antibody-mediated rejection (AAMR) is the subject of much research. It is diagnosed by C4d staining at biopsy and circulating donor-specific antibodies (DSA). The combination of intensive plasmapheresis and intravenous immunoglobulin (IVIG) has been recognized as an effective treatment for AAMR. We report our single-center experience on AAMR treatment. Materials and MethodsWe treated 23 transplanted patients (group A) with protein-A immunoadsorption (IA) and 7 patients (group B) with double-filtration plasmapheresis. All patients were treated with IVIG (400 mg/kg/d). Basic immunosuppression included cyclosporine, steroids, azathioprine, and antilymphocyte globulin or monoclonal antibodies (OKT3). A subgroup of 3 patients (3/7; group B1) was treated with photopheresis. ResultsIn both groups, the mean number of extracorporeal procedures was 7.3 ± 4.5 and 5.5, respectively; the mean duration of treatment was 12.3 ± 10.2 and 14.5 days, respectively. In group A, we observed negative cross-matching in 96% after mean of 18 days; 1 patient died from sepsis, and 6 lost their grafts. In group B, negative circulating DSA were observed in all patients after a mean of 25 days, and 1 patient lost their allograft. ConclusionsIn our observation, the 2 extracorporeal procedures had similar effects in terms of graft survival, DSA removal, and cross-match negativity (group A 74% vs 86%; 95.6% vs 100%). IA was faster for DSA removal. In our opinion, the higher costs of IA suggests its use just in high-risk cases, such as in hyperimmune or sensitized patients. Further studies are necessary to improve our knowledge.