The role of inflammation in intravenous immune globulin-mediated hemolysis

Toxic epidermal necrolysis with thrombocytopenia induced by intravenous immunoglobulin: a case report and mini review

BACKGROUND

Toxic epidermal necrolysis (TEN), a severe cutaneous hypersensitivity reaction induced particularly by drugs, is diagnosed when there is a fever of ≥ 38 °C, mucocutaneous symptoms, a rash with multiple erythema, and skin peeling of ≥ 30% of the body surface area. The mortality rate of TEN is high, and thrombocytopenia during treatment can lead to severe outcomes. Intravenous immunoglobulin (IVIg) is used when steroids are ineffective in TEN and may improve mortality; however, thrombocytopenia is a rare adverse event associated with IVIg use. We report the case of thrombocytopenia during IVIg therapy for TEN. We also reviewed previous reports to learn more about the clinical course and mechanism of IVIg-induced thrombocytopenia.

CASE PRESENTATION

An 83-year-old man with end-stage renal failure on hemodialysis was diagnosed with TEN. After an inadequate response to pulse methylprednisolone therapy, IVIg (400 mg/kg/day) was administered for 5 days. He developed thrombocytopenia after IVIg administration, leading to the diagnosis of thrombocytopenia due to IVIg after excluding other diseases. The platelet count began to increase approximately 10 days after IVIg administration.

CONCLUSIONS

When IVIg is administered for TEN, the risk of thrombocytopenia should be recognized and the platelet count should be carefully monitored.

Hemolytic anemia associated with intravenous immunoglobulin in Kawasaki disease

BACKGROUND

The administration of high-dose intravenous immunoglobulin (IVIG) is a standard treatment for the management of Kawasaki disease (KD). IVIG is known to be a highly effective and safe treatment.

CASE PRESENTATION

We report the development of hemolytic anemia in seven children receiving repeated doses of IVIG. The children were aged 3-44 months and included 4 girls and 3 boys. All children received 10% IVIG and a second course of immunoglobulin because they did not respond to the first course of immunoglobulin. Two received high-dose aspirin (50 mg/kg), and five received low-dose aspirin (5 mg/kg). Two patients required additional methylprednisolone pulse therapy (30 mg/kg) after the second dose of immunoglobulin, and three patients received oral prednisolone therapy for defervescence. Three patients showed coronary artery dilation during hospitalization and normalized within two months. Pretreatment hemoglobin averaged 11.3-14.2 g/dL, and post-hemolytic anemia hemoglobin ranged from 7.4 to 9.6 g/dL, with a difference of 1.7-6.8 g/dL. Reticulocytes were increased to 3.3-13.2%. Peripheral blood smears showed normochromic normocytic anemia, and anisopoikilocytosis. All children were positive for warm-type antibodies with IgG+, C3d- in direct antiglobulin test, and the blood group was A + in five and B + in two. None of the patients received immunomodulatory therapy or red blood cell transfusions. They were followed for a year and all recovered.

CONCLUSION

Especially, in non-O blood group KD patients who are refractory to initial IVIG and require a second dose of IVIG or 10% formulation the possibility of immune hemolytic anemia should be carefully considered, and close follow-up should be maintained after therapy.

A retrospective analysis of haemolytic reactions to intravenous immunoglobulin using data from the Transfusion-Transmitted Injuries Surveillance System (Ontario)

BACKGROUND AND OBJECTIVES

Haemolysis can occur following intravenous immunoglobulin (IVIG) infusion. Haemovigilance data were analysed using a novel approach for including two control groups with no haemolysis to IVIG. Objectives included a summary of all reactions to IVIG, rate estimates and analysis of haemolytic reactions including risk factors.

MATERIALS AND METHODS

Canadian haemovigilance data from Ontario (2013-2021), IVIG distribution and transfusion data from the blood supplier, and data from a large local transfusion registry were used. An 'other-reactions' control group included patients with IVIG reactions that were not haemolytic, and registry patients with no-reaction were the 'no-reaction controls'. Descriptive analysis and two logistic regression models for the different control groups were performed.

RESULTS

One thousand one hundred and seventy reactions were included. Most common were febrile non haemolytic (26.1%), minor allergic (24.5%) and IVIG headache (15.3%) followed by haemolytic 10.9% (128/1170). Haemolytic reaction rates decreased over time: rates since 2020 estimated between 1.5 and 2.9/1000 kg IVIG used. The regression model for other-reaction controls identified two risk factors for haemolysis: non-O blood group recipients compared with group O recipients (p value = 0.0106) and IVIG dose per 10 g increase (OR 1.359; 95% CI 1.225-1.506). The model using no-reaction controls gave similar results and also showed no pre-medication was associated with a higher risk of haemolysis (OR 29.084; 95% CI 1.989-425.312).

CONCLUSION

The frequency of haemolytic reactions has decreased over time. We confirmed non-O blood group recipients and IVIG dose as risk factors for haemolysis and raise the hypothesis that no pre-medication may increase the risk of haemolysis.

Don't neglect the rare adverse event with intravenous immunoglobulin: Hemolytic anemia

Intravenous immunoglobulin (IVIG) associated hemolytic anemia is an under-recognized complication of IVIG therapy. The incidence of this adverse event is not clear. Patients at high risk for IVIG-associated hemolytic anemia include non-O blood group recipients and those undergoing high-dose administration for inflammatory or autoimmune disorders. Here, two different cases of IVIG-associated hemolytic anemia are demonstrated. The first patient, a 66 year-old male with Guillain-Barré syndrome, had a severe attack for which erythrocyte replacement was required. Mild hemolysis was detected during IVIG administration in the second patient, a 57 year-old female with chronic immune thrombocytopenic purpura. Following IVIG termination, the hemolysis diminished gradually. Although it is rare and often manageable, clinicians should be aware of and monitor patients for hemolytic anemia following IVIG therapy.

An optimized microplate-based method to evaluate complement-dependent hemolysis mediated by intravenous immunoglobulins (IVIG)

Hemolytic reactions can cause serious complications after administration of Intravenous Immunoglobulin (IVIG), due to passive transfer of anti-A and anti-B IgG antibodies (isoagglutinins). A maximum allowable amount of isoagglutinins is established in the US and EU for licensed IVIG, as measured by a specified direct hemagglutination test (DHAT). Despite this limit, reports of hemolysis have increased over time, raising the question of how well the DHAT predicts clinically significant hemolysis. This study was undertaken to develop a microplate-based complement-dependent hemolysis assay (CDHA) that reproducibly measures functional hemolytic activity of IVIG, for assessment of IVIG products. An IVIG working reference reagent (NIBSC 14/160) was qualified as an assay control and for quantitation purposes. Hemolytic activities of 36 IVIG product lots encompassing seven brands and including 6 clinically hemolytic lots were measured. Hemolytic activity varied among IVIG product brands, and to a lesser extent, from lot-to-lot for individual brands. Correlation between the CDHA and DHAT was not robust which may reflect imprecision of the DHAT method or additional variables that influence complement-dependent hemolysis after opsonization. In conclusion, the CDHA provides a simple, specific, and sensitive tool for IVIG product characterization and investigation of hemolytic events by manufacturers, researchers, and regulatory authorities.

A prospective observational study of the incidence, natural history, and risk factors for intravenous immunoglobulin-mediated hemolysis

BACKGROUND

Intravenous Immune Globulin (IVIG) is used to treat numerous immune-mediated and inflammatory conditions. There is growing awareness of hemolysis, occasionally severe, as a side-effect of this therapy. While most cases are associated with anti-A and/or anti-B isoagglutinins, the frequency and mechanism of hemolysis remain poorly characterized.

STUDY DESIGN AND METHODS

A prospective observational study was conducted to determine incidence, natural history and risk factors for IVIG-mediated hemolysis. A total of 99 infusions of high-dose IVIG (2 g/kg or higher) administered to 78 non-group O patients were monitored and graded according to Canadian IVIG Hemolysis Pharmacovigilance Group. Serum ferritin and C3/C4 levels were monitored as indicators of macrophage activation and complement consumption, respectively. Supplementary investigations included assessment for ABO zygosity, Secretor status, FcR polymorphisms, eluate IgG subclass, monocyte monolayer assay, and a panel of cytokines.

RESULTS

Hemolysis was observed in 32 of 99 (32%) of infusions, with 19 of 99 (19%) grade 2 or higher. Hemolysis was only apparent 5-10 days after a completed IVIG infusion in 84% of cases and was associated with increases in serum ferritin without complement-consumption. In univariate analysis, increased risk was observed in group AB patients, first-time IVIG recipients, those not taking immuosuppressive medications, or patients treated with a specific IVIG brand; however, in multivariate analysis, product association was no longer observed. No other patient- or practice-related risk factors were identified.

CONCLUSION

IVIG-mediated hemolysis is common and frequently severe. Monitoring for 5-10 days following an infusion should be considered in non-O patients receiving high-dose IVIG with known risk factors.

The utility of a monocyte monolayer assay in the assessment of intravenous immunoglobulin-associated hemolysis

BACKGROUND

Hemolysis following the administration of intravenous immunoglobulin (IVIG) is an important adverse event (AE). While the monocyte monolayer assay (MMA) has been used to predict in vivo hemolysis when serologically incompatible blood may be transfused, it has also been shown to correlate with IVIG-associated hemolysis. In this study, the MMA was examined for its utility in assessing the risk of hemolysis after IVIG.

STUDY DESIGN AND METHODS

Forty-two non-blood group O patients receiving high-dose IVIG (≥2 g/kg) were examined using an autologous and allogeneic MMA. Hemolysis was defined by a drop in hemoglobin of ≥1 g/L, a positive direct antiglobulin test (DAT) and eluate, and a decrease in haptoglobin or increase in lactate dehydrogenase and/or reticulocytes.

RESULTS

Forty-two patients provided 50 assessable postinfusion samples, with hemolysis observed in 20 (40%) of cases. Autologous MMA using post-IVIG red blood cells significantly correlated with clinical outcomes when compared to allogeneic MMA (P = .0320 vs .5806, t test). No significant difference in receiver operating characteristics was observed when comparing autologous MMA testing against DAT for the diagnosis of IVIG-associated hemolysis. However, when using samples collected 5 to 10 days after receipt of high-dose IVIG, the autologous MMA had higher sensitivity than the DAT.

CONCLUSION

MMA testing with autologous monocytes collected 5 to 10 days after receipt of high-dose IVIG can be used for the diagnosis of IVIG-associated hemolysis and may be of particular value in cases in which the Day 5 to 10 DAT is negative.

Mouse Models of Rheumatoid Arthritis for Studies on Immunopathogenesis and Preclinical Testing of Fc Receptor-Targeting Biologics

<b><i>Background:</i></b> Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes inflammation, swelling, and pain in the joints and involves systemic complications. Mouse models of RA have been extensively used to model the pathogenesis of RA and to develop effective therapies. Although many components of the immune system have been studied in these models, the role of crystallizable fragment (Fc) gamma receptors (FcγRs) in RA has been sorely neglected. The aim of this review was to introduce the different mouse models of RA and to describe the different drug development strategies that have been tested in these models to target FcγR function, with the focus being on drugs that have been made from the Fc of immunoglobulin G (IgG). <b><i>Summary:</i></b> Evidence suggests that FcγRs play a major role in immune complex-induced inflammation in autoimmune diseases, such as RA. However, there is limited knowledge on the importance of FcγRs in the human disease even though there has been extensive work in mouse models of RA. Numerous mouse models of RA are available, with each model depicting certain aspects of the disease. Induced models of RA have nonspecific immune activation with cartilage-directed autoimmunity, whereas spontaneous models of RA develop without immunization, which results in a more chronic form of arthritis. These models have been used to test FcγR-targeting monoclonal antibodies, intravenous immunoglobulin (IVIg), subcutaneously administered IVIg, and recombinant Fcs for their ability to interact with and modify FcγR function. Recombinant Fcs avidly bind FcγRs and exhibit enhanced therapeutic efficacy in mouse models of RA. <b><i>Key Message:</i></b> The therapeutic utility of targeting FcγRs with recombinant Fcs is great and should be explored in human clinical trials for autoimmune diseases, such as RA.

Anti-A/B isoagglutinin reduction in an intravenous immunoglobulin product and risk of hemolytic anemia: a hospital-based cohort study

BACKGROUND

Intravenous immunoglobulins (IVIG) are derived from large human plasma pools. IVIG-associated hemolytic anemia (HA) is a known class effect, likely attributed to dose-dependent passive transfer of anti-A/B isoagglutinins. Two isoagglutinin reduction steps were implemented in the manufacturing process of Privigen (human 10% liquid IVIG): exclusion of high-anti-A-titer donors in 2013, replaced by specific immunoaffinity chromatography in 2015. We aim to estimate the clinical effectiveness of both measures.

STUDY DESIGN AND METHODS

Using the US hospital-based Premier Healthcare Database, three Privigen cohorts were generated based on calendar periods indicative of manufacturing changes: Period 1 (baseline) January 2008 to December 2012, Period 2 (high-anti-A-titer donor exclusion) October 2013 to December 2015, and Period 3 (immunoaffinity chromatography) October 2016 to April 2019. HA within a 10-day at-risk period after Privigen administrations was identified from review of patient record summaries. Incidence rate ratios (IRRs) were estimated from Poisson regression (Period 1 reference) adjusting for hospital setting, sex, age, Privigen indication, dose, and first use.

RESULTS

Crude incidence rates of HA were 1.49 per 10,000 person-days in Period 1 (38 HA, 9439 patients), 1.01 in Period 2 (20 HA, 7710 patients), and 0.14 in Period 3 (3 HA, 7759 patients). Adjusted IRR for HA in Period 2 was 0.71 (95% confidence interval [CI], 0.41-1.23), and in Period 3 was 0.10 (0.03-0.33) compared with Period 1. The IRR for HA in Period 3 compared with Period 2 was 0.14 (95% CI, 0.04-0.47).

CONCLUSION

Implementation of immunoaffinity chromatography in Privigen manufacturing resulted in a significant 90% reduction of HA risk. HA has become a rare event in association with Privigen use.

Isoagglutinin reduction in intravenous immunoglobulin (IgPro10, Privigen) by specific immunoaffinity chromatography reduces its reporting rates of hemolytic reactions: an analysis of spontaneous adverse event reports

BACKGROUND

Hemolysis is an infrequent but recognized and potentially serious adverse effect of intravenous immunoglobulin (IVIG). Relatively elevated hemolysis reporting rates were seen with some IVIG products with high anti-A/B isoagglutinin content, among which IgPro10 (Privigen, CSL Behring). For IgPro10, two isoagglutinin reduction measures were successively implemented: 1) anti-A donor screening and 2) immunoaffinity chromatography (IAC; Ig IsoLo)-based isoagglutinin reduction step included in the production process. The aim of this analysis was to investigate the effects of these isoagglutinin reduction measures on the reporting rates of IgPro10 hemolysis worldwide.

STUDY DESIGN AND METHODS

Between February 2008 and December 2018, hemolysis reports from the CSL Behring Global Safety Database were analyzed in relationship to changes in IVIG IgPro10 production methods. Further analysis classified hemolysis reports by indication and blood group.

RESULTS

Median (minimum-maximum) anti-A/anti-B titers were 32 (8-64)/16 (8-32) at baseline, 32 (8-64)/16 (8-32) after donor screening, and 8 (8-32)/4 (2-8) after implementation of IAC. The reporting rate of hemolytic reactions per 1000 kg IgPro10 sold was 4.05 cases at baseline, 2.00 after donor screening, and 0.50 after implementation of IAC. In 2018, there were seven reports of hemolytic reactions; representing 0.18 cases per 1000 kg IgPro10 sold, with a reduction of 95.6% versus baseline.

CONCLUSION

Following implementation of the IAC isoagglutinin reduction step, spontaneous reports of hemolytic events with IgPro10 were significantly and consistently reduced versus IgPro10 without isoagglutinin reduction, offering patients a more favorable benefit-risk profile.

Screening of multiple hemoprotein-specific aptamers and their applications for the binding, quantification, and extraction of hemoproteins in a microfluidic system

The blood hemoproteins, albumin, γ-globulin, and fibrinogen, serve as biomarkers for a variety of human diseases, including kidney and hepatorenal syndromes. Therefore, there is a need to quickly and accurately measure their concentrations in blood. Herein, nucleic acid aptamers demonstrating high affinity and specificity toward these hemoproteins were selected via systematic evolution of ligands by exponential enrichment, and their ability to capture their protein targets was assessed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by a tetramethyl benzidine assay. The limits of detection for the hemoproteins were all around 10-3 μM, and dissociation constant values of 131, 639, and 29nM were obtained; capture rates were measured to be 66%, 71%, and 61%, which is likely to be suitable for clinical diagnostics. Furthermore, a multi-layer microfluidic disk system featuring hemoprotein-specific aptamers for depleting hemoproteins was demonstrated. It could be a promising approach to use aptamers to replace conventional antibodies.

[Intravenous immunoglobulin-induced thrombocytopenia in patient with chronic inflammatory demyelinating polyneuropathy]

A 69-year-old man was admitted to our hospital because of dysesthesia in right palm and left upper limb, gait disturbance, and muscle weakness in both lower limbs. At the same time of neurological impairment appeared, he developed pemphigoid. Lumber MRI showed swelling of cauda equina nerve root. We diagnosed as chronic inflammatory demyelinating polyneuropathy based on an electrophysiological examination, and 2 courses of intravenous immunoglobulin therapy (IVIG) were initiated. After the treatments, symptoms improved immediately. However, thrombocytopenia was seen after each treatment which began on the second day of treatment start, reaching the lowest point from about 10 to 14 days, and improved naturally from 10 to 15 days after the end of IVIG. Difficulty in hemostasis was seen during dialysis due to thrombocytopenia. As a cause of thrombocytopenia, formation of IgG-platelet complexes could be considered, and the presence of multiple inflammatory diseases which activated Fcγ receptors play key roles could be a risk for IVIG related thrombocytopenia.

Isoagglutinin-reduced immunoglobulin retains efficacy in mouse models of immune thrombocytopenia and rheumatoid arthritis and is less likely to cause intravenous immunoglobulin-associated hemolysis

BACKGROUND

Immunoglobulin therapy including intravenous immunoglobulin (IVIg) has been used as an effective treatment for autoimmune/inflammatory conditions with few side effects. However, high‐dose IVIg (1‐2 g/kg) has been recognized as a cause of hemolytic anemia in non–blood group O patients. Hemolysis when observed has been due to anti‐A/anti‐B isoagglutinins contained in the IVIg. Recently, an isoagglutinin‐reduced IVIg, whereby the anti‐A and anti‐B titers have been reduced by immunoaffinity chromatography, has been introduced; however, whether this new product is as efficacious as nonreduced immunoglobulin (Ig) or will result in less IVIg‐associated hemolysis has not been resolved.

STUDY DESIGN AND METHODS

We used in vitro phagocytosis by monocytes and proinflammatory/anti‐inflammatory macrophages, with isoagglutinin‐reduced and ‐nonreduced Ig opsonized group A₁, B, and A₁B red blood cells, to estimate clinical significance of the IgG isoagglutinins. We also used immune thrombocytopenia (ITP) and rheumatoid arthritis (RA) mouse models to examine the in vivo efficacy of isoagglutinin‐reduced versus ‐nonreduced Ig on the amelioration of the diseases.

RESULTS

In contrast to nonreduced Ig, phagocytosis was largely absent when isoagglutinin‐reduced Ig was used at a concentration equivalent to a patient receiving 2 g/kg.

The in vivo efficacy of isoagglutinin‐reduced versus nonreduced Ig on the amelioration of experimental ITP and RA was similar, indicating no loss of efficacy due to the chromatographic removal of isoagglutinins.

CONCLUSION

Isoagglutinin‐reduced Ig should have efficacy similar to nonreduced Ig and result in less IVIg‐associated hemolysis.

Comprehensive Management Considerations of Select Noncardiac Organ Systems in the Cardiac Intensive Care Unit

As the acuity and complexity of pediatric patients with congenital cardiac disease have increased, there are many noncardiac issues that may be present in these patients. These noncardiac problems may affect clinical outcomes in the cardiac intensive care unit and must be recognized and managed. The Pediatric Cardiac Intensive Care Society sought to provide an expert review of some of the most common challenges of the respiratory, gastrointestinal, hematological, renal, and endocrine systems in pediatric cardiac patients. This review provides a brief overview of literature available and common practices.

The first case of severe acute hemolytic transfusion reaction caused by anti-Sc2

BACKGROUND

Alloantibodies to the low-frequency antigen Scianna-2 (Sc2) have been implicated in cases of hemolytic disease of the fetus and newborn but never in hemolytic transfusion reactions (HTRs); thus, the clinical significance of anti-Sc2 has yet to be fully addressed.

STUDY DESIGN AND METHODS

A 26-year-old woman with thalassemia presented rigors, fever, nausea, abdominal pain, and hemolytic biochemistry after exposure to 75 mL of plasma-reduced red blood cells (RBCs). The RBC unit was issued by electronic crossmatch but was 3+ incompatible on recrossmatch by gel indirect antiglobulin test (IAT). The patient had anti-Sc2 previously identified, but considered to be clinically insignificant. The transfusion history was reviewed and a monocyte monolayer assay (MMA) was performed.

RESULTS

The patient was investigated for a RBC reaction 9 years prior, when she developed symptoms of HTR. The RBC unit was crossmatched by immediate spin due to consistent screen negativity. Full crossmatch found the RBC 1+ incompatible by gel IAT with both pre/post samples, while direct antiglobulin test was negative (pre) and 1+ immunoglobulin G positive (post). The antibody remained unidentified and she was committed to gel IAT crossmatch. Two-years later, the specificity to Sc2 was deduced when one RBC unit was found 3+ incompatible. Finally, the transfusion reaction reported herein occurred when she received by happenstance RBCs from the same donor who was associated with the remote reaction 9 years earlier. MMA yielded highly positive phagocytic indices only for Sc2+ RBCs, including the donor's RBCs that triggered the severe HTR.

CONCLUSION

This is the first case of HTR caused by anti-Sc2 confirmed by clinical findings and MMA.

High-dose intravenous immunoglobulin is strongly associated with hemolytic anemia in patients with Kawasaki disease

BACKGROUND

Hemolysis is a reported side effect of intravenous immunoglobulin (IVIG) therapy in adults, but pediatric data are scarce. We determined the frequency of IVIG-associated hemolysis in patients with Kawasaki disease (KD) and characterized risk factors for hemolysis. We hypothesized that hemolysis is more common in children with KD than adults with other disorders, and hemolysis risk is related to IVIG dose and degree of inflammation.

STUDY DESIGN AND METHODS

This was an 8-year, single-center, retrospective cohort study. A total of 419 KD patients were identified; 123 had pre- and post-treatment complete blood counts allowing for assessment of anemia. Hemolytic anemia was defined as decrease in hemoglobin after IVIG greater than 1 g/dL with immunohematologic or biochemical studies supporting hemolysis.

RESULTS

123 patients were stratified as having hemolysis (n = 18, 15%) or nonhemolysis (n = 105, 85%). Patients with hemolysis were more likely to have complete versus incomplete KD (65% vs. 39%, p = 0.04) and refractory versus nonrefractory course (78% vs. 16%, p < 0.001). Patients receiving 4 g/kg versus 2 g/kg IVIG were more likely to hemolyze (89% vs. 34%, p < 0.001). Patients with hemolysis had mostly non-O blood group (94%), positive direct antiglobulin tests (89%), and positive eluates (72%). Two-thirds of patients with hemolysis required RBC transfusion.

CONCLUSIONS

Hemolysis occurred in 15% of KD patients evaluated for anemia and is strongly associated with high-dose (4 g/kg) IVIG. KD patients receiving high-dose IVIG should have close hematologic monitoring to identify hemolysis.

Role of intravenous immunoglobulin in the treatment of Kawasaki disease

Intravenous immunoglobulin (IVIg) is a purified plasma product that is used for many immune-deficient conditions and autoimmune conditions. Use of IVIg for treatment for Kawasaki disease (KD) is critical for control of inflammation. The American Heart Association (AHA) recommends a single infusion of 2 g/kg preferably given during the first 10 days of illness. In this review, we have discussed the possible mechanisms of action of IVIg in KD and its clinical usage in this condition.

Intravenous immunoglobulin-induced acute thrombocytopenia

BACKGROUND

Intravenous immunoglobulin (IVIG) has known efficacy in various hematologic conditions, including immune thrombocytopenic purpura.

STUDY DESIGN AND METHODS

We present the clinical course of a patient with splenic marginal zone lymphoma, who developed acute thrombocytopenia on three consecutive episodes, with nadir counts of 27 × 10⁹ , 50 × 10⁹ , and 9 × 10⁹ /L, upon administration of Intratect IVIG for hypogammaglobulinemia. An immunofluorescence test applying flow cytometry and monoclonal antibody immobilization of platelet antigens (MAIPA) assay were used to evaluate the reaction between IgG present in the IVIG preparations and the patient's or healthy donors' platelets (PLTs).

RESULTS

A strong direct binding reaction was observed between the patient's PLTs and Intratect IgG using both methods. A similar reaction failed to materialize with controls. Binding was not antigen specific according to MAIPA.

CONCLUSIONS

This is the first reported case of thrombocytopenia as a possible adverse effect of IVIG.

Hemolysis related to intravenous immunoglobulins is dependent on the presence of anti-blood group A and B antibodies and individual susceptibility

BACKGROUND

Patients treated with intravenous immunoglobulins (IVIG) rarely experience symptomatic hemolysis. Although anti-A and anti-B isoagglutinins from the product are involved in most cases, the actual mechanisms triggering hemolysis are unclear.

STUDY DESIGN AND METHODS

A prospective, open-label, multicenter, single-arm clinical trial in 57 patients with immune thrombocytopenia treated with IVIG (Privigen, CSL Behring) was conducted.

RESULTS

Twenty-one patients received one infusion (1 g/kg) and 36 received two infusions (2 × 1 g/kg) of IVIG. After a study duration of more than 2 years, no cases of clinically significant hemolysis as defined in the protocol were identified. Data of patients with mild hematologic and biochemical changes were analyzed in more detail. Twelve cases (10/23 patients with blood group A1 and 2/11 patients with blood group B, all having received 2 g/kg IVIG) were adjudicated as mild hemolysis (median hemoglobin [Hb] decrease, -3.0 g/dL); Hb decreases were transient, with partial or full recovery achieved by last visit. Eighteen patients (31.6%), all with non-O blood group, of whom 16 (88.9%) received 2 g/kg IVIG, fulfilled post hoc criteria for hemolytic laboratory reactions. Red blood cell (RBC) eluates of all direct antiglobulin test-positive samples were negative for non-ABO blood group antibodies. Blood groups A and B antigen density on RBCs appeared to be a risk factor for hemolytic laboratory reactions. Platelet response to treatment was observed in 42 patients (74%); eight of 12 patients with complete response had blood group A1.

CONCLUSION

Isoagglutinins are involved in clinically nonsignificant hemolysis after treatment with IVIG, but individual susceptibility varies greatly.

Early platelet and leukocyte decline in patients with neuroinflammatory disorders after intravenous immunoglobulins

BACKGROUND AND PURPOSE

Intravenous immunoglobulins (IVIGs) are a common therapy in patients with neuroinflammatory disorders, especially chronic inflammatory demyelinating polyradiculoneuropathy or Guillain-Barré syndrome. Hematological toxicities upon IVIG infusion are a known side effect and still an important subject of investigation.

METHODS

Laboratory results and data for clinical efficacy and tolerability of 62 patients with neuroinflammatory disorders treated with IVIG (0.4 g/kg bodyweight per day over 5 days) at the Department of Neurology, University of Duisburg-Essen, Germany, were retrospectively analyzed. Blood samples were taken before and 1 day after IVIG administration.

RESULTS

In pre-treated and first-time treated patients, there was a significant decrease in white blood cell count (WBC) (8.10 ± 2.85/nl to 5.61 ± 2.50/nl, P < 0.001, n = 57) and platelets (255 ± 72/nl to 215 ± 66/nl, P < 0.001, n = 57). Mild hemolysis of red blood cells was found in patients who received IVIG for the first time (red blood cell count 4.61 ± 0.67/pl to 4.28 ± 0.52/pl, hemoglobin 13.7 ± 1.7 g/l to 13.0 ± 1.7 g/l, P < 0.001, n = 40). Hemolysis was associated with less tolerability of IVIG treatment and clinical efficacy was accompanied with a higher decline of WBC (not significant).

CONCLUSIONS

Next to mild hemolysis, a significant decrease in WBC and platelets can be detected early after high dose IVIGs in patients with neuroinflammatory disorders. Changes in blood counts may be possible markers for clinical efficacy and tolerability. Patients with low blood counts in advance should be particularly closely monitored whilst on IVIG treatment.

Immunoglobulin-induced hemolysis, splenomegaly and inflammation in patients with antibody deficiencies

IgG replacement for primary antibody deficiencies is a safe treatment administered to prevent recurrent infections and reduce mortality. Recently, several reports described acute hemolytic episodes following IgG administration due to a passive transfer of blood group alloantibodies, including anti-A, anti-B, as well as anti-Rh antibodies. Here, we reviewed and discussed the consequences of passively transferred RBCs antibodies. The chronic passive transfer of alloantibodies might also cause a subclinical condition due to a compensated extravascular chronic hemolysis with poorly understood consequences. This phenomenon might possibly represent an unrecognized cause of splenomegaly and might contribute to inflammation in patients with primary antibody deficiencies.

Pathogenesis and mechanisms of antibody-mediated hemolysis

BACKGROUND

The clinical consequences of antibodies to red blood cells (RBCs) have been studied for a century. Most clinically relevant antibodies can be detected by sensitive in vitro assays. Several mechanisms of antibody-mediated hemolysis are well understood. Such hemolysis after transfusion is reliably avoided in a donor-recipient pair, if one individual is negative for the cognate antigen to which the other has the antibody.

STUDY DESIGN AND RESULTS

Mechanisms of antibody-mediated hemolysis were reviewed based on a presentation at the Strategies to Address Hemolytic Complications of Immune Globulin Infusions Workshop addressing intravenous immunoglobulin (IVIG) and ABO antibodies. The presented topics included the rates of intravascular and extravascular hemolysis; immunoglobulin (Ig)M and IgG isoagglutinins; auto- and alloantibodies; antibody specificity; A, B, A,B, and A1 antigens; A1 versus A2 phenotypes; monocytes-macrophages, other immune cells, and complement; monocyte monolayer assay; antibody-dependent cell-mediated cytotoxicity; and transfusion reactions due to ABO and other antibodies.

CONCLUSION

Several clinically relevant questions remained unresolved, and diagnostic tools were lacking to routinely and reliably predict the clinical consequences of RBC antibodies. Most hemolytic transfusion reactions associated with IVIG were due to ABO antibodies. Reducing the titers of such antibodies in IVIG may lower the frequency of this kind of adverse event. The only way to stop these events is to have no anti-A or anti-B in the IVIG products.