Immune-Mediated Hemolytic Anemia

A single center experience for clinical evaluation of paroxysmal cold hemoglobinuria and Donath-Landsteiner testing

BACKGROUND

Paroxysmal cold hemoglobinuria (PCH) is a rare form of autoimmune hemolytic anemia (AIHA), mainly affecting children. The diagnosis and management are challenging due to similarities to other causes for AIHA and limited availability to Donath-Landsteiner (DL) testing.

STUDY DESIGN AND METHODS

In this single-center retrospective study, we aimed to characterize the clinical presentation and outcomes of PCH patients, defined as having positive Donath-Landsteiner antibodies, compared to a cohort of AIHA patients.

RESULTS

DL-positive patients were observed to have higher lactate dehydrogenase levels and lower reticulocyte counts compared to DL-negative patients, although this was not statistically significant. We also observed that using steroids in DL-positive patients did not significantly impact their recovery.

DISCUSSION

Our findings support the limited published data on PCH patients and further prompt larger multicenter studies to further characterize these patients so that they are more readily identified, especially in centers where DL antibody testing is not readily available.

Fostamatinib for the treatment of warm antibody autoimmune hemolytic anemia: Phase 2, multicenter, open-label study

Patients with relapsed warm antibody autoimmune hemolytic anemia (wAIHA) have limited treatment options. Fostamatinib is a potent, orally administered spleen tyrosine kinase inhibitor approved in the United States and Europe for the treatment of adults with chronic immune thrombocytopenia (ITP). This phase 2 study evaluated the response to fostamatinib, administered at 150 mg BID orally with or without food in adults with wAIHA and active hemolysis with hemoglobin (Hgb) <10 g/dL who had failed at least one prior treatment. Hemoglobin levels and safety assessments were performed at visits every 2 weeks. The primary endpoint was Hgb >10 g/dL with an increase of ≥2 g/dL from baseline by week 24 without rescue therapy or red blood cell transfusion. Eleven of 24 (46%) patients achieved the primary endpoint. Increases in median Hgb were detected at week 2 and sustained over time. Median lactate dehydrogenase levels and reticulocyte counts generally declined over time with little change in median haptoglobin levels. The most common adverse events (AEs) were diarrhea (42%), fatigue (42%), hypertension (27%), dizziness (27%), and insomnia (23%). AEs were manageable and consistent with the fostamatinib safety database of over 3900 patients across multiple diseases (rheumatoid arthritis, B-cell lymphoma, COVID-19, and ITP). No new safety signals were detected. Fostamatinib may be a promising therapeutic option for wAIHA. A randomized, double-blind, phase 3 study is nearing completion.

First Report of Severe Autoimmune Hemolytic Anemia During Eltrombopag Therapy in Waldenström Macroglobulinemia-Associated Thrombocytopenia

Autoimmune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA) can be observed in Waldenström macroglobulinemia (WM). The autoimmune disorders are primarily mediated by autoimmune monoclonal gammopathy, but drug-induced hemolysis should also be considered. Herein, we presented the case of a 63-year-old female WM patient complicated with ITP, who was admitted to our department with a complaint of abdominal pain. After first half of bortezomib/dexamethasone/rituximab (BRD) chemotherapy, her platelet level recovered, but subsequently decreased to extremely low level (around 1–2×10⁹/L), and the patient suffered from platelet transfusion refractoriness. During the management of refractory thrombocytopenia, the patient developed severe hemolytic anemia, and further tests confirmed warm AIHA. FcγRIIα polymorphism test showed that the patient had FcγRIIα-131RH, which implied that the AIHA may not be WM-related. Given the effects of ibrutinib in controlling WM, secondary AITP and AIHA, ibrutinib single treatment was started, which quickly corrected the thrombocytopenia within five days, but not hemolysis. With a relatively safe platelet level, eltrombopag was stopped, and the hemolysis relieved three days after eltrombopag withdrawal. This is the first report on eltrombopag-induced AIHA in the management of WM-associated ITP.

Paroxysmal Nocturnal Hemoglobinuria: An Underestimated Cause of Pediatric Thromboembolism

Paroxysmal nocturnal hemoglobinuria (PNH) is a chronic disease caused by complement-mediated hemolysis. Clinical symptoms include intravascular hemolysis, nocturnal hemoglobinuria, thromboses, cytopenia, fatigue, abdominal pain, and a strong tendency toward bone marrow failure. It is a rare disease, especially in children, with high mortality rates without appropriate treatment.

We here present the case of a 17-year-old girl with unprovoked muscle vein thrombosis. Flow cytometric analysis showed deficiency of glycosyl-phosphatidylinositol-anchored membrane proteins on all three hematopoietic cell lines and confirmed the diagnosis of PNH. Treatment with the monoclonal antibody eculizumab achieved long-term remission.

As flow cytometry is normally not part of the routine diagnostics for pediatric thrombosis, awareness is crucial and PNH is important to consider in all children with thrombosis at atypical sites and abnormalities in blood counts with regard to hemolysis and cytopenia.

Autoimmune hemolytic anemia in solid organ transplantation-The role of immunosuppression

Hemolysis after solid organ transplantation can be caused by both immune and non-immune-mediated mechanisms, and the evaluation must take into account issues distinctive to the post-transplant period. Autoimmune hemolytic anemia usually occurs within the first year and has been attributed to immunosuppressive treatment, infections, or underlying post-transplant lymphoproliferative disorder. Review of the literature revealed 59 cases with autoimmune hemolytic anemia mostly in children after liver transplantation. Almost all of the patients at the time of diagnosis received immunosuppression with tacrolimus, and first-line treatment with steroids and/or intravenous immunoglobulin was ineffective for complete remission. Rituximab was used as second-line treatment especially in patients with underlying lymphoproliferative disorders whereas sirolimus showed encouraging results.

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.

Flow cytometry screening for paroxysmal nocturnal hemoglobinuria: A single-center experience in Saudi Arabia

BACKGROUND

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal hematopoietic stem cell disorder, characterized by the deficiency of glycosylphosphatidylinositol (GPI) that anchors proteins in cell membranes. PNH is manifest variously with hemoglobinuria, thrombosis, or bone marrow failure. This retrospective study was aimed at assessing the incidence and characteristics of patients diagnosed with PNH in the King Fisal Specialist Hospital and research center.

METHODS

Patients referred for PNH diagnosis at King Faisal Specialist Hospital and Research Centre, Riyadh, during the 2-year period (2012-2013) were included in the analysis. Peripheral blood samples were used for multi-parametric flow cytometry analysis based on fluorescent inactive aerolysin (FLAER), and the markers, CD235a and CD59 on red blood cells (RBCs), and CD14, CD45, CD64, CD24, and CD15 on white blood cells (WBCs) exclusively monocytes and granulocytes. Univariate analysis of the disease characteristics was performed.

RESULTS

Of the 366 samples submitted for PNH screening, 14 were positive (4%) and 11 were evaluable. Of the 11 patients analyzed, 8 patients (73%) presented with aplastic anemia, 1 patient (9%) each with pancytopenia, Budd-Chiari syndrome, and immune thrombocytopenia purpura. All samples showed type II and III GPI-deficient clones with a median clone size of 15% (range, 0.7%-56%) in the RBCs, and 63% (range, 3.8%-100%) in WBCs (monocytes and granulocytes).

CONCLUSIONS

This study confirms the rarity of PNH and its predominant presentation as aplastic anemia or thrombosis in a Saudi Arabian population, similar to the worldwide incidence.

Primary cold agglutinin-associated lymphoproliferative disease: a B-cell lymphoma of the bone marrow distinct from lymphoplasmacytic lymphoma

Primary chronic cold agglutinin disease is a rare hemolytic disease mediated by monoclonal IGHV4-34-encoded cold agglutinins with a predominant specificity for the blood group antigen I. Bone marrow from 54 patients was studied to type the underlying lymphoproliferative disorder better. Bone marrow biopsies showed circumscribed intra-parenchymatous nodules with small monotonous monoclonal B cells in 40/54 patients (median infiltration: 10% of marrow cells) with a CD20(+), IgMs(+), IgDs(+), CD27(+), CD5(-/+), CD11c(-), CD23(-), CD38(-) immunophenotype. Neither plasmacytoid cytological features nor expression of plasma cell differentiation-associated transcription factors MUM1, XBP1 and BLIMP1 were noted in these B cells. However, a limited number of mature monoclonal IgM(+), IgD(-) plasma cells were present outside the lymphoid nodules and were diffusely scattered throughout the marrow. Of interest, the MYD88 L265P mutation, typical of lymphoplasmacytic lymphoma, was not detected (17/17 cases). Somatically mutated monoclonal IGHV4-34 gene rearrangement was demonstrated in eight patients with frozen samples (mean sequence homology 95.4%). However, mutations of BCL6 intron 1 were not demonstrated, except in one patient, suggesting that the lymphoma cells had not matured in the germinal center. In conclusion, cold agglutinin-associated lymphoproliferative disease displays homogeneous histological and immunophenotypic features. The absence of plasmacytoid cells, the presence of plasma cells predominantly outside the nodular lymphoid infiltrates, IGHV4-34 restriction and absence of MYD88 L265P mutation strongly suggest that cold agglutinin-associated lymphoproliferative disease is a distinct entity that is different from lymphoplasmacytic lymphoma.

Paroxysmal cold hemoglobinuria caused by an IgM-class Donath-Landsteiner antibody

We report on a 4-year-old boy who developed paroxysmal cold hemoglobinuria (PCH) following the first dose of a seven-valent pneumococcal conjugate vaccine. He was admitted because of dark urine after exposure to cold air. Laboratory tests indicated anemia, increased serum indirect bilirubin and lactate dehydrogenase, and decreased serum haptoglobin. Donath-Landsteiner (D-L) test was positive. The D-L antibody belonged to the IgM class and exhibited anti-P specificity. Symptoms and signs subsided after supportive care without any medication. Although PCH is often associated with viral or bacterial infection and is caused by IgG-class D-L antibodies with anti-P specificity, this case was unique because a D-L antibody of the IgM class with anti-P specificity caused PCH after immunization with a pneumococcal vaccine.

Cold agglutinin disease in fibrolamellar hepatocellular carcinoma: a rare association with a rare cancer variant

Cold agglutinin disease (CAD) is a rare autoimmune hemolytic anemia. Although it can occur secondary to lymphoproliferative disorders and autoimmune or infectious diseases, CAD is rarely reported as secondary to solid tumors. We report a case of a woman aged 18 years diagnosed with a well-differentiated hepatocellular carcinoma of the fibrolamellar subtype, who was shown to have CAD also. Her general condition, including CAD, improved after targeted therapy with sorafenib for the hepatocellular carcinoma and only conservative measures for the CAD that consisted of avoidance of cold. In summary, although it is an extremely rare association and less common than lymphoproliferative disorders, CAD can be associated with solid tumors.

Spleen tyrosine kinases: biology, therapeutic targets and drugs

Spleen tyrosine kinase (Syk) is an intriguing protein tyrosine kinase involved in signal transduction in a variety of cell types, and its aberrant regulation is associated with different allergic disorders and antibody-mediated autoimmune diseases such as rheumatoid arthritis, asthma and allergic rhinitis. Syk also plays an important part in the uncontrolled growth of tumor cells, particularly B cells. For these reasons, Syk is considered one of the most interesting biological targets of the last decade, as proved by the great number of papers and patents published, and the possibility of treating these pathologies by means of Syk kinase inhibitors has led to a great interest from the pharmaceutical and biotech industry.

[Rheumatoid arthritis and autoimmune hemolysis: B-cell depletion for remission induction in a patient with rheumatoid arthritis and cold agglutinin disease]

Autoimmune hemolysis is a rare complication of systemic rheumatic diseases. We report on a 68-year-old female patient with established, long-standing rheumatoid arthritis, who complained of progressive weakness and worsening of her arthralgia under therapy with leflunomide. Physical and laboratory examination revealed autoimmune hemolysis due to cold agglutinin disease. As hemolysis and arthritis were refractory to steroid treatment, B-cell depletion with rituximab was performed leading to a marked reduction of hemolytic parameters as well as remission of her rheumatoid arthritis.

Multicenter phase 3 study of the complement inhibitor eculizumab for the treatment of patients with paroxysmal nocturnal hemoglobinuria

The terminal complement inhibitor eculizumab was recently shown to be effective and well tolerated in patients with paroxysmal nocturnal hemoglobinuria (PNH). Here, we extended these observations with results from an open-label, non-placebo-controlled, 52-week, phase 3 clinical safety and efficacy study evaluating eculizumab in a broader PNH patient population. Eculizumab was administered by intravenous infusion at 600 mg every 7 +/- 2 days for 4 weeks; 900 mg 7 +/- 2 days later; followed by 900 mg every 14 +/- 2 days for a total treatment period of 52 weeks. Ninety-seven patients at 33 international sites were enrolled. Patients treated with eculizumab responded with an 87% reduction in hemolysis, as measured by lactate dehydrogenase levels (P < .001). Baseline fatigue scores in the FACIT-Fatigue instrument improved by 12.2 +/- 1.1 points (P < .001). Eculizumab treatment led to an improvement in anemia. The increase in hemoglobin level occurred despite a reduction in transfusion requirements from a median of 8.0 units of packed red cells per patient before treatment to 0.0 units per patient during the study (P < .001). Overall, transfusions were reduced 52% from a mean of 12.3 to 5.9 units of packed red cells per patient. Forty-nine patients (51%) achieved transfusion independence for the entire 52-week period. Improvements in hemolysis, fatigue, and transfusion requirements with eculizumab were independent of baseline levels of hemolysis and degree of thrombocytopenia. Quality of life measures were also broadly improved with eculizumab treatment. This study demonstrates that the beneficial effects of eculizumab treatment in patients with PNH are applicable to a broader population of PNH patients than previously studied. This trial is registered at http://clinicaltrials.gov as NCT00130000.

Primary chronic cold agglutinin disease: an update on pathogenesis, clinical features and therapy

Chronic cold agglutinin disease (CAD) is a subgroup of autoimmune hemolytic anemia. Primary CAD has traditionally been defined by the absence of any underlying or associated disease. The results of therapy with corticosteroids, alkylating agents and interferon-a have been poor. Cold reactive immunoglobulins against erythrocyte surface antigens are essential to pathogenesis of CAD. These cold agglutinins are monoclonal, usually IgMκ auto antibodies with heavy chain variable regions encoded by the V_H4-34 gene segment. By flowcytometric and immunohistochemical assessments, a monoclonal CD20⁺κ⁺B-lymphocyte population has been demonstrated in the bone marrow of 90% of the patients, and lymphoplasmacytic lymphoma is a frequent finding. Novel attempts at treatment for primary CAD have mostly been directed against the clonal B-lymphocytes. Phase 2 studies have shown that therapy with the chimeric anti-CD20 antibody rituximab produced partial response rates of more than 50% and occasional complete responses. Median response duration, however, was only 11 months. In this review, we discuss the clinical and pathogenetic features of primary CAD, emphasizing the more recent data on its close association with clonal lymphoproliferative bone marrow disorders and implications for therapy. We also review the management and outline some perspectives on new therapy modalities.

Platelet glycoprotein VI-related clinical defects

Human patients with defects associated with the platelet collagen receptor, glycoprotein (GP)VI, are rare and usually described as having a mild bleeding disorder. However, here we review clinical profiles of patients with familial or acquired GPVI defects, revealing the bleeding defect is often severe and associated with immune dysfunction. GPVI is a member of the immunoreceptor family, and co-expressed on platelets with Fc receptor gamma-chain (FcRgamma). Ligand binding to GPVI leads to activation of platelet integrins, in particular alpha(IIb)beta(3) that mediates platelet aggregation; and activation of endogenous platelet metalloproteinases resulting in ectodomain shedding and release of a soluble GPVI fragment. Increasing evidence supports the functional importance of GPVI/FcRgamma in thrombus formation at arterial shear rates, and expression levels of platelet GPVI may be a marker of thrombotic risk. Over the past 20 years, patients have been reported with GPVI-related defects involving: (i) an acquired deficiency, resulting from (a) anti-GPVI autoantibodies or (b) other causes; or (ii) a congenital deficiency, where (c) GPVI is not expressed or (d) is expressed in a dysfunctional form with defective signalling to alpha(IIb)beta(3). Clinical consequences of GPVI-related defects may be uniquely informative about the role of platelet GPVI in health and disease.

A case of recurrent paroxysmal cold hemoglobinuria with the different temperature thresholds of Donath-Landsteiner antibodies

In this article, we first report a case of recurrent paroxysmal cold hemoglobinuria with serologic confirmation. On 2 occasions, the Donath-Landsteiner (DL) antibodies belonged to an IgM subclass and showed neither anti-P nor anti-I specificity. Furthermore, it is very interesting that the temperature thresholds of DL antibodies were different on each occasion. Although acute paroxysmal cold hemoglobinuria is considered to be self-limited and transient, we should be careful of its possible recurrence. DL tests must be repeated after the complete recovery from the first episode, with careful attention to several possible causes of false-negative DL tests.

Toxicity as a result of immunostimulation by biologics

The immune system has evolved highly effective mechanisms of surveillance and defense against foreign pathogens, and is also thought to act in surveillance and suppression of cancer. Thus, a predominant goal of immune system-based therapies is to normalize or enhance the host immune response in the areas of infectious disease and oncology. This review considers general approaches used for therapeutic immunostimulation, alterations in immune response mechanisms that occur with these treatments and the syndromes that commonly arise as a result of these changes. Because nonclinical studies of these therapies are conducted in animal models as the basis for predicting potential human toxicities, this review also considers the value of nonclinical testing to predict human toxicity.

A familial platelet function disorder associated with abnormal signalling through the glycoprotein VI pathway

The platelet collagen receptor, glycoprotein (GP)VI, of the immunoreceptor family forms a complex with the von Willebrand factor (VWF) receptor, GPIb-IX-V, critical for initiating thrombus formation. GPVI is co-associated with Fc receptor gamma-chain (FcRgamma), which contains a cytoplasmic immunoreceptor tyrosine-based activation motif domain, involved in activation of Syk, and a signalling cascade leading to (i) activation of alpha(IIb)beta(3), which binds VWF and fibrinogen and mediates platelet aggregation, and (ii) metalloproteinase-mediated shedding of the GPVI ectodomain (blocked by Syk inhibitors), a key mechanism for regulating GPVI surface expression. In this study, we report a familial case of abnormal platelet aggregation with dysfunctional signalling through GPVI that uniquely demonstrates divergent alpha(IIb)beta(3)-activating and GPVI-shedding pathways. The patient is a 60-year-old female with a history of immune disorders, excessive bleeding from childhood and a life-threatening haemorrhage post-trauma. Platelet aggregation to ADP, thrombin receptor-agonist peptide or ristocetin/VWF was normal (indicating normal expression and function of alpha(IIb)beta(3)), but platelet aggregation to GPVI agonists, collagen, collagen-related peptide, or convulxin, was defective. Both GPVI/FcRgamma expression and ligand-induced GPVI ectodomain shedding were normal, confirming expression of functional GPVI/FcRgamma, but suggesting a signalling defect downstream of Syk. A genetic defect in GPVI/Fcgamma signalling compromising platelet function is hypothesised in this family.

Cold agglutinin induced autoimmune hemolytic anemia and NK-cell leukemia: a new association

Cold agglutinin induced autoimmune hemolytic anemia is uncommonly associated with leukemia and lymphomas. We present a case of a young Mexican female presenting with a cold agglutinin hemolytic anemia with expression of a rare Pr antigen specificity and an aggressive NK-cell leukemia. Our patient had a rapid fatal course. To our knowledge this is the first reported case of such an association.

[Autoimmune hemolytic anemia: diagnosis and management]

Autoimmune hemolytic anemia (AIHA) is diagnosed in the presence of anemia, usually macrocytic and of variable intensity, reticulocytosis, and a positive direct and/or indirect antiglobulin test, after ruling out other types of hemolytic anemia. A positive direct antiglobulin test alone is not sufficient to diagnose AIHA and may be positive in many patients without anemia or negative in some patients with AIHA. AIHA may be classified into two major categories according to the optimal temperature of antibody activity: warm-reacting autoantibodies (usually IgG) optimal around 37 degrees C and cold-reacting autoantibodies, optimal at 4 degrees C (usually IgM). This classification guides the selection of tests and treatment. AIHA is widely reported to be associated with a variety of other diseases, although these associations are often fortuitous. A minimal set of useful investigations is appropriate since AIHA may be secondary to viral infections, lymphoid malignancies, or autoimmune disorders such as lupus. Transfusion should remain rare in AHAI, but close contact with the transfusion service is necessary if it is to succeed. As for many autoimmune and/or systemic diseases, numerous types of treatment have been proposed but have not been validated in controlled multicenter studies. These are necessary to improve the management of these rare disorders.

Autoimmune hemolytic anemia in childhood: serologic features in 100 cases

BACKGROUND

Red blood cell (RBC) autoimmunization is a relatively uncommon cause of anemia in children and presents some differences from those of adults. Due to its frequency, autoimmune hemolytic anemia (AIHA) in childhood has prompted very few studies, and the literature consists mostly of sporadic case histories. The objective of this study was to stress the importance of an appropriate serologic diagnosis in suspected cases.

STUDY DESIGN AND METHODS

This report describes the immunohematologic features of 100 patients with AIHA studied in the Immunohaematologic Unit of Blood Bank, "La Sapienza" University of Rome. The patients were diagnosed in the same department from 1983 to 2003.

RESULTS

The peak incidence of AIHA was in the first 4 years of life. No sex predominance was noted. Warm AIHA was the most common type of acquired immune hemolytic anemia; it comprised 64 of the 100 patients, whereas 26 patients showed a cold AIHA. Associated AIHA showed a slightly more frequent incidence (54/100) compared to idiopathic forms of AIHA (46/100).

CONCLUSIONS

In this study serologic records of 100 children with confirmed AIHA are reported. This series, much larger than any previously reported, is critically reviewed and analyzed to delineate the immunologic features of the disease in childhood.

Association of a common dog leucocyte antigen class II haplotype with canine primary immune-mediated haemolytic anaemia

Immune-mediated haemolytic anaemia (IMHA) is the commonest immune-mediated disease of the dog, representing a major health concern to this species. The aim of this investigation was to determine whether genetic susceptibility to IMHA is associated with genes of the canine major histocompatibility complex (MHC; dog leucocyte antigen system, DLA). Samples were collected from 108 dogs with primary idiopathic, Coombs' positive IMHA. This diseased population was subdivided on the basis of Coombs' test results into two groups: 1) dogs with dominant warm-reactive immunoglobulin (Ig) G haemagglutinins and (2) dogs with an additional or dominant cold-reactive IgM haemagglutinin. The DLA class II alleles and haplotypes of the diseased population were characterised, and these data were compared with those derived from a breed-matched control cohort and a much larger group of DLA-typed dogs. Two haplotypes were increased in the patient group: DLA-DRB1*00601/DQA1*005011/DQB1*00701 (in the group with warm-reactive IgG haemagglutinins only) and DLA-DRB1*015/DQA1*00601/DQB1*00301 (in both groups, but more so in the group with cold-reactive IgM haemagglutinins). One haplotype, DLA-DRB1*001/DQA1*00101/DQB1*00201, was decreased in the total patient group, but this decrease was limited to the warm-reactive IgG haemagglutinins group, and it was actually increased in the cold-reactive IgM haemagglutinins group. A second haplotype, DLA-DRB1*015/DQA1*00601/DQB1*02301, was also decreased in the total patient group, and this decrease was found in both subgroups. In addition, all haplotypes carrying DLA-DRB1*001 were significantly increased in the cold-reactive IgM haemagglutinins group. When the overall patient group was divided on the basis of individual breeds with more than six animals represented, each of the haplotypes could be shown to be implicated in one of the breeds. Thus, it was apparent that different breeds had different MHC associations with canine IMHA, which is similar to the observation that different human ethnic groups can have different HLA associations with the same immune-mediated disease.

Evaluation of liposomal clodronate in experimental spontaneous autoimmune hemolytic anemia in dogs

OBJECTIVES

Liposomal clodronate (dichloromethylene diphosphonate) has been used to deplete macrophages and block clearance of opsonized cells in mouse models of autoimmune disease. However, liposomal clodronate (LC) has not been previously evaluated in a large-animal spontaneous autoimmune disease model. Therefore, the safety and efficacy of LC treatment was assessed in normal dogs and in dogs with spontaneous autoimmune hemolytic anemia (AIHA).

METHODS

LC was administered intravenously first to healthy dogs and then to dogs with spontaneous, severe AIHA to determine if the treatment was safe and could block clearance of opsonized red blood cells (RBCs) in vivo. Studies were also conducted to assess the in vitro effects of LC on dog macrophages and dendritic cells.

RESULTS

Intravenous infusion of low doses of LC was well tolerated and blocked clearance of opsonized RBCs in normal dogs in vivo. LC was taken up by splenic macrophages and dendritic cells in vivo, and induced killing of macrophages and dendritic cells in vitro. Seven dogs with severe, spontaneous AIHA were treated with LC in a pilot study. Treatment was well tolerated, 2 of 7 LC-treated dogs with AIHA had a decrease in RBC clearance, and LC-treated dogs had significantly increased survival times compared to historical control dogs matched for disease severity.

CONCLUSIONS

These results indicate that LC can be safely administered intravenously to dogs and that even relatively low doses are capable of blocking RBC clearance and improving outcomes in a spontaneous large-animal model of AIHA. Therefore, additional studies of LC for treatment of autoantibody-mediated cytopenias in dogs and humans may be warranted.

Vincristine-loaded platelet infusion for treatment of refractory autoimmune hemolytic anemia and chronic immune thrombocytopenia: rethinking old cures

We report our experience with vincristine-loaded platelet infusion in patients with refractory immune thrombocytopenia (ITP), autoimmune hemolytic anemia (AIHA), and Evans syndrome. Ten patients with symptomatic thrombocytopenia and/ or hemolytic anemia who failed to respond to two to six different treatment modalities, including corticosteroids and splenectomy, were treated with infusion of vincristine-loaded platelets. Platelets were harvested by plateletpheresis from a healthy ABO compatible blood donor and incubated with 5 mg vincristine. Excess of vincristine was removed, and platelets were resuspended in 50 ml plasma and infused over 30 min. All 10 patients responded, and 6 of them achieved complete remission. The response was prompt, occurring 3-8 days after vincristine-loaded platelet infusion. Two patients with AIHA are still in remission 9 and 8 years posttreatment with no maintenance treatment. Three ITP patients achieved persisted partial response for 6 years, 5 years, and 11 months; in the remaining 5 patients the response lasted for 2-5 months. No side effects were seen. Our results suggest that this inexpensive and well-tolerated treatment modality may be a useful approach in patients with ITP and AIHA refractory to primary therapy.

Sirolimus rescue for tacrolimus-associated post-transplant autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) has been reported to occur after renal transplantation, and typically does so in the first few weeks post-transplant. We report on a 3-yr-old child who developed cold AIHA nearly 1 yr after an ABO identical, living donor renal transplant from his mother. Numerous transfusions, pulse steroids, repeat plasma exchange treatments, and IVIG were unsuccessful. Nearly 3 wk into his illness, tacrolimus was changed to cyclosporine, and then to sirolimus, and resulted in a prompt response. He currently has a normal renal function and a normal hemoglobin level on sirolimus monotherapy.

Insuficiencia renal aguda secundaria a hemoglobinuria paroxística al frío

Paroxysmal cold hemoglobinuria is a type of hemolytic anemia that mainly affects children. Tubular renal injury induced by the heme pigment in intravascular hemolysis is a rare cause of renal failure. We describe the case of a 5-year-old boy who presented with dehydration and dark urine a few hours after exposure to cold. The child had had an upper respiratory infection the previous week. He developed anemia and acute renal failure. The direct antiglobulin test was positive with anti-C3c and C3d. The diagnosis of paroxysmal cold hemoglobinuria was confirmed by the presence of biphasic antibody in the Donath-Landsteiner test.