Antibody-mediated rejection despite inhibition of terminal complement

Terminal complement blockade has been shown to decrease the incidence of early acute antibody-mediated rejection (eAMR) in the first month after positive cross-match kidney transplant recipients, yet some patients still develop eAMR. The current study investigated possible mechanisms of eAMR despite eculizumab treatment. Of the 26 patients treated with eculizumab, two developed clinical eAMR and another patient developed histologic signs of eAMR without graft dysfunction ('subclinical eAMR'). Twenty-three did not have histologic injury on early surveillance biopsies. All 26 patients had therapeutic levels of eculizumab and showed complete blockade of complement in hemolytic assays. High levels of donor-specific alloantibody (DSA) including total IgG, IgG3, and C1q+ DSA were present in patients with and without eAMR, and none correlated well with eAMR. In contrast, IgM DSA was present in only four patients after transplantation: the two patients with clinical eAMR, one patient with subclinical AMR, and one patient without eAMR (P = 0.006 correlation with eAMR). Both clinical eAMR episodes were easily treated with plasma exchange which removed IgM more completely and rapidly than IgG, resulting in normalization of function and histology. These data suggest a possible role of antidonor IgM DSA in the pathogenesis of eAMR in patients treated with terminal complement blockade (ClinicalTrials.gov Identifier: NCT00670774).

Extracorporeal photopheresis for chronic graft-versus-host disease: a systematic review and meta-analysis

Background

The safety of extracorporeal photopheresis (ECP) in steroid-refractory chronic graft-versus-host disease (SR-cGVHD) has been explored in multiple studies but reported response rates (RR) vary significantly across studies.

Methods

We conducted a meta-analysis to assess the efficacy of ECP for SR-cGVHD. A search of electronic databases for studies published between 1984 and 2012 was conducted. End points included RR: complete response (CR), overall response rates (ORR), and organ-specific RR. The initial search generated 312 studies, of which 18 met the selection criteria (N=595). A random effects model was used for pooled rates.

Results

Pooled CR rates and ORR were 29% (confidence interval [CI], 19-42%) and 64% (CI, 65-82%), respectively. One-year overall survival was available for 4 studies only and was 49% (CI, 29-70%). The pooled RR for skin, liver, ocular, oral, lung, gastrointestinal and musculoskeletal SR-cGVHD was 74%, 68%, 60%, 72%, 48%, 53%, and 64%, respectively. There was a significant heterogeneity among studies due to differences in ECP schedules and duration. No significant differences in responses to ECP for pediatric and adult populations were found. Sensitivity analysis could not be undertaken due to a limited number of prospective studies.

Conclusion

ECP is an effective therapy for oral, skin, and liver SR-cGVHD, with modest activity in lung and gastrointestinal SR-cGVHD.

American Society for Apheresis guidelines on the use of apheresis in clinical practice: practical, concise, evidence-based recommendations for the apheresis practitioner

The 6th Guidelines on the use of therapeutic apheresis in clinical practice published by the American Society of Apheresis provide practical, concise, and evidence based guidance for the apheresis medicine practitioner. The overall format of the Guidelines has remained unchanged with the 6th edition, compared to the 5th edition, with enhancements in the committee process of creating the guidelines. Because of changes in the writing committee structure, a number of changes have occurred in the ASFA category and recommendation grade for the use of apheresis in the treatment for a number of previously categorized clinical indications. In addition, eight new indications for apheresis, twenty three new clinical situations for previously categorized diseases, and ten new apheresis treatments for previously categorized disorders have been added. The 6th Guidelines continue to be an invaluable resource for those involved in apheresis medicine.

Guidelines on the use of therapeutic apheresis in clinical practice-evidence-based approach from the Writing Committee of the American Society for Apheresis: the sixth special issue

The American Society for Apheresis (ASFA) JCA Special Issue Writing Committee is charged with reviewing, updating and categorizating indications for therapeutic apheresis. Beginning with the 2007 ASFA Special Issue (Fourth Edition), the committee has incorporated systematic review and evidence-based approach in the grading and categorization of indications. This Sixth Edition of the ASFA Special Issue has further improved the process of using evidence-based medicine in the recommendations by consistently applying the category and GRADE system definitions, but eliminating the "level of evidence" criteria (from the University HealthCare Consortium) utilized in prior editions given redundancy between GRADE and University HealthCare Consortium systems. The general layout and concept of a fact sheet that was utilized in the Fourth and Fifth Editions, has been largely maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis in a specific disease entity. This article consists of 78 fact sheets (increased from 2010) for therapeutic indications in ASFA categories I through IV, with many diseases categorized having multiple clinical presentations/situations which are individually graded and categorized.

Genetic and biochemical analyses in dyslipidemic patients undergoing LDL apheresis

OBJECTIVE

Familial hypercholesterolemia (FH) can be due to mutations in LDLR, PCSK9, and APOB. In phenotypically defined patients, a subset remains unresponsive to lipid-lowering therapies and requires low density-lipoprotein (LDL) apheresis treatment. In this pilot study, we examined the genotype/phenotype relationship in patients with dyslipidemia undergoing routine LDL apheresis.

DESIGN

LDLR, APOB, and PCKS9 were analyzed for disease-causing mutations in seven patients undergoing routine LDL apheresis. Plasma and serum specimens were collected pre- and post-apheresis and analyzed for lipid concentrations, Lp(a) cholesterol, and lipoprotein particle concentrations (via NMR).

RESULTS

We found that four patients harbored LDLR mutations and of these, three presented with xanthomas. While similar reductions in LDL-cholesterol (LDL-C), apolipoprotein B, and LDL particles (LDL-P) were observed following apheresis in all patients, lipid profile analysis revealed the LDLR mutation-positive cohort had a more pro-atherogenic profile (higher LDL-C, apolipoprotein B, LDL-P, and small LDL-P) pre-apheresis.

CONCLUSION

Our data show that not all clinically diagnosed FH patients who require routine apheresis have genetically defined disease. In our small cohort, those with LDLR mutations had a more proatherogenic phenotype than those without identifiable mutations. This pilot cohort suggests that patients receiving the maximum lipid lowering therapy could be further stratified, based on genetic make-up, to optimize treatment.

The mechanisms of action of plasma exchange

The initial description of therapeutic plasma exchange (TPE) in an animal model was published almost 100 years ago. Since that time, this treatment has been applied to a wide variety of diseases but limited research has been published examining the mechanisms of action of TPE. The therapeutic effects of TPE could include the removal of pathological substances from the blood, such as monoclonal paraproteins and autoantibodies, as well as the replacement of deficient plasma components when plasma is used as a replacement fluid. Beyond these potential mechanisms, other possible mechanisms include possible alterations in lymphocyte proliferation and function that could sensitize these cells to immunosuppressant and chemotherapeutic agents and alterations in the immune system including changes in B and T cell numbers and activation, increased T suppressor function, and alteration in T-helper cell type 1/2 (Th1/Th2) ratio. Much remains unknown about the mechanisms of action of TPE, indicating a need for basic research into this therapy.

A multicenter evaluation of a new therapeutic plasma exchange procedure

BACKGROUND

The AMICUS (Fenwal, Inc.) was cleared in the United States for platelet (PLT) and plasma collection in 1996 with subsequent clearances for the collection of other blood products. Although not previously used for therapeutic plasma exchange (TPE), new disposables, software, and hardware were developed to enable TPE on the AMICUS.

STUDY DESIGN AND METHODS

A multicenter, randomized, nonblinded, crossover paired treatment protocol was performed. Thirty patients with orders for at least two TPE procedures were randomly assigned to the AMICUS or the COBE Spectra (TerumoBCT) for the first treatment. Each patient was crossed over to the other device using the same procedure settings from the first procedure. The primary objective compared efficiency of plasma removal (EPR) with secondary objectives of comparing PLT and hemoglobin (Hb) waste plasma content, coagulation factor and complement activation, fluid balance tracking accuracy, procedure length, and adverse events.

RESULTS

The EPR for the AMICUS (81.9 ± 7.62%) was superior to that of the COBE Spectra (75.2 ± 6.29%; p = 0.00001). The AMICUS also demonstrated statistically higher fluid balance accuracy (99.84%) compared to that of the COBE Spectra (98.83%; p < 0.0001) and a statistically shorter procedure time (103.9 ± 30.8 vs. 110.5 ± 27.1 min, p < 0.001). No significant differences with regard to PLT and Hb content in the waste plasma, change in patient PLT count, or changes in markers of coagulation and complement cascade activation were seen. Frequency and severity of adverse reactions were similar.

CONCLUSION

The AMICUS separator can effectively perform TPE. The AMICUS demonstrated superior plasma removal efficiency compared to the COBE Spectra with no evidence of significant differences in PLT removal, hemolysis, and coagulation or complement activation.

Plasma exchange and glucocorticoid dosing in the treatment of anti-neutrophil cytoplasm antibody associated vasculitis (PEXIVAS): protocol for a randomized controlled trial

BACKGROUND

Granulomatosis with polyangiitis (GPA, Wegener's) and microscopic polyangiitis (MPA) are small vessel vasculitides collectively referred to as anti-neutrophil cytoplasm antibody-associated vasculitis (AAV). AAV is associated with high rates of morbidity and mortality due to uncontrolled disease and treatment toxicity. Small randomized trials suggest adjunctive plasma exchange may improve disease control, while observational evidence suggests that current oral glucocorticoid doses are associated with severe infections in patients with AAV. A randomized study of both plasma exchange and glucocorticoids is required to evaluate plasma exchange and oral glucocorticoid dosing in patients with AAV.

METHODS/DESIGN

PEXIVAS is a two-by-two factorial randomized trial evaluating adjunctive plasma exchange and two oral glucocorticoid regimens in severe AAV. Five hundred patients are being randomized at centers across Europe, North America, Asia, and Australasia to receive plasma exchange or no plasma exchange, and to receive standard or reduced oral glucocorticoid dosing. All patients receive immunosuppression with either cyclophosphamide or rituximab. The primary outcome is the time to the composite of all-cause mortality and end-stage renal disease.PEXIVAS is funded by the National Institute of Health Research (UK), the Food and Drug Administration (USA), the National Institutes of Health (USA), the Canadian Institute of Health Research (Canada), the National Health and Medical Research Council (Australia), and Assistance Publique (France). Additional in-kind supplies for plasma exchange are provided by industry partners (TerumoBCT, Gambro Australia, and Fresenius Australia).

DISCUSSION

This is the largest trial in AAV undertaken to date. PEXIVAS will inform the future standard of care for patients with severe AAV. The cooperation between investigators, funding agencies, and industry provides a model for conducting studies in rare diseases.

TRIAL REGISTRATION

Current Controlled Trials: (ISRCTN07757494) and clinicaltrials.gov: (NCT00987389).

Lot-to-lot variability in HLA antibody screening using a multiplexed bead-based assay

BACKGROUND

Identifying antibodies to HLA (anti-HLA) by solid-phase assays is used to screen blood donors to mitigate transfusion-related acute lung injury risk. Various cutoffs for detection assays have been proposed in the literature; however, these do not take into consideration lot-to-lot variability of commercially available assays.

STUDY DESIGN AND METHODS

Samples from 93 nontransfused males were tested using five different lots of a multiplex bead-based anti-HLA detection kit. A subset of 17 samples was tested on 5 days using a single lot. An additional 96 samples from donations with varied anti-HLA levels were tested using kits from two different lots. Results were reported as a normalized background (NBG) ratio.

RESULTS

For the 93 nontransfused donors, NBG values generated using the reference lot were significantly higher than those obtained with three of the four comparator lots. However, for the 96 samples with low-, moderate-, and higher-level anti-HLA, Class I (CL-I) values were 1.4 times lower and Class II (CL-II) values were 1.2 times lower using the reference versus comparator lot. For CL-I antibodies the between-lot standard deviation (SD) was 1.36 (95% confidence interval [CI], 1.19-1.60), while the between-day SD was 1.27 (95% CI, 1.08-1.52). Similarly, for CL-II antibodies the between-lot SD was 0.81 (95% CI, 0.70-0.95), while the between-day SD was 0.50 (95% CI, 0.43-0.60).

CONCLUSIONS

There is interlot variability in the tested HLA detection assay as well as significant bias between lots. It may be reasonable to develop a new cutoff when a new lot is obtained.

Five-year outcomes in living donor kidney transplants with a positive crossmatch

Renal transplant candidates with high levels of donor-specific anti-HLA antibodies have low transplantation rates and high mortality rates on dialysis. Using desensitization protocols, good short-term outcomes are possible in "positive crossmatch kidney transplants (+XMKTx)", but long-term outcome data are lacking. The aim of the current study was to determine actual 5-year graft outcomes of +XMKTx. We compared graft survival and the functional and histologic status of 102 +XMKTx to 204 -XMKTx matched for age and sex. Actual 5-year death-censored graft survival was lower in the +XMKTx group (70.7% vs. 88.0%, p < 0.01) and chronic injury (glomerulopathy) was present in 54.5% of surviving grafts. Graft survival was higher in recipients with antibody against donor class I only compared with antibody against class II (either alone or in combination with class I) (85.3% vs. 62.6%, p = 0.05) and was similar to -XMKTx (85.3 vs. 88.0%, p = 0.64). Renal function and proteinuria ranged across a wide spectrum in all groups reflecting the different histological findings at 5 years. We conclude that when compared to -XMKTx, +XMKTx have inferior outcomes at 5 years, however, almost half of the surviving grafts do not have glomerulopathy and avoiding antibodies against donor class II may improve outcomes.

Ticlopidine-, clopidogrel-, and prasugrel-associated thrombotic thrombocytopenic purpura: a 20-year review from the Southern Network on Adverse Reactions (SONAR)

Thienopyridine-derivatives (ticlopidine, clopidogrel, and prasugrel) are the primary antiplatelet agents. Thrombotic thrombocytopenic purpura (TTP) is a rare drug-associated syndrome, with the thienopyridines being the most common drugs implicated in this syndrome. We reviewed 20 years of information on clinical, epidemiologic, and laboratory findings for thienopyridine-associated TTP. Four, 11, and 11 cases of thienopyridine-associated TTP were reported in the first year of marketing of ticlopidine (1989), clopidogrel (1998), and prasugrel (2010), respectively. As of 2011, the FDA received reports of 97 ticlopidine-, 197 clopidogrel-, and 14 prasugrel-associated TTP cases. Severe deficiency of ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) was present in 80% and antibodies to 100% of these TTP patients on ticlopidine, 0% of the patients with clopidogrel-associated TTP (p < 0.05), and an unknown percentage of patients with prasugrel-associated TTP. TTP is associated with use of each of the three thienopyridines, although the mechanistic pathways may differ.

Drug-associated thrombotic microangiopathies

Thrombotic microangiopathy is a pathological process that results in thrombocytopenia, schistocytes, and organ ischemia. A wide variety of causes of thrombotic microangiopathy have been described, each associated with a different pathological stimulus and predisposition toward certain vascular territories. This review will summarize our understanding of key drugs that have been classically and newly associated with thrombotic microangiopathy as well as mention of treatment options focusing on the role of plasma exchange.

Plasma exchange as a therapeutic option in patients with neurologic symptoms due to antibodies to voltage-gated potassium channels: a report of five cases and review of the literature

Antibodies to voltage-gated potassium channels (VGKC) are associated with acquired neuromyotonia, limbic encephalitis, and Morvan's syndrome. The antibodies are often not associated with malignancy and have shown good clinical response to immunomodulatory therapies. A record review identified five patients with laboratory evidence of antibodies to VGKC who underwent plasma exchange (PE) as part of their immunosuppressive therapy for neurologic disease. Four of the patients presented with limbic encephalitis and one with neuromyotonia. Symptoms included memory impairment, seizures, and personality changes. All PE were 1.0 volume and were performed on an every-other-day schedule. Replacement fluid was 5% normal serum albumin except when a bleeding risk was identified and then fresh frozen plasma was added. Four of five patients were also receiving concurrent immunosuppressive therapy including corticosteroids. Of the five patients treated with PE, three had sustained improvement in symptoms for 6-17 months following PE. Two patients did not have signs of improvement at a limited follow-up. One patient had recurrence of her symptoms, which responded to additional PE. These cases, as well as the reports in the literature, suggest that PE could be a useful adjunctive therapy for patients with VGKC antibodies and neurologic symptoms.

Fresh red blood cell transfusion and short-term pulmonary, immunologic, and coagulation status: a randomized clinical trial

RATIONALE

Transfusion-related pulmonary complications are leading causes of morbidity and mortality attributed to transfusion. Observational studies suggest an important role for red blood cell (RBC) storage duration in these adverse outcomes.

OBJECTIVES

To evaluate the impact of RBC storage duration on short-term pulmonary function as well as immunologic and coagulation status in mechanically ventilated patients receiving RBC transfusion.

METHODS

This is a double-blind, randomized, clinical trial comparing fresh (≤5 d of storage) versus standard issue single-unit RBC transfusion in adult intubated and mechanically ventilated patients. The primary outcome is the change in pulmonary gas exchange as assessed by the partial pressure of arterial oxygen to fraction of inspired oxygen concentration ratio (ΔPa(O(2))/Fi(O(2))). Secondary outcomes include changes in immune and coagulation status.

MEASUREMENTS AND MAIN RESULTS

Fifty patients were randomized to receive fresh RBCs and an additional 50 patients to standard issue RBCs. Median storage age was 4.0 days (interquartile range, 3.0-5.0) and 26.5 days (interquartile range, 21.0-36.0) in the fresh RBC group and standard issue RBC group, respectively. No differences were noted in the primary outcome of ΔPa(O(2))/Fi(O(2)) (difference between the mean ΔPa(O(2))/Fi(O(2)) in the standard issue RBC group vs. the fresh RBC group, -11.5; 95% confidence interval, -35.3 to 12.3; P = 0.22). Similarly, no significant differences were noted in markers of immunologic or coagulation status.

CONCLUSIONS

In this randomized clinical trial, no differences were noted in early measures of pulmonary function or in immunologic or coagulation status when comparing fresh versus standard issue single-unit RBC transfusion. Clinical trial registered with ClinicalTrials.gov (NCT00751322).

Low-density lipoprotein apheresis: principles and indications

Low-density lipoprotein (LDL) apheresis describes a group of apheresis techniques that selectively remove apolipoprotein B-containing lipoproteins producing an acute reduction in LDL-cholesterol (LDL-C). Six devices are available for the removal of LDL-C while sparing other important plasma components. The LDL-apheresis (LDL-A) is not routinely used for the treatment of hypercholesterolemia, which usually responds to medical management, but is used to treat familial hypercholesterolemia, an inherited metabolic abnormality resulting in premature death due to progressive coronary artery disease, and to treat patients who fail medical management. The mechanism of action of the available LDL-A devices, reactions that can occur with these treatments, and the role of this specialized apheresis technique in the treatment of hypercholesterolemia are described.