New Insights in the Pathogenesis of Autoimmune Hemolytic Anemia

Hemin-induced reactive oxygen species triggers autophagy-dependent macrophage differentiation and pro-inflammatory responses in THP-1 cells

The toxic effect of oxidized-heme, also known as hemin, is implicated in developing adverse clinical outcome in various hematolytic diseases. To simulate and reconstruct the molecular events associated with hemin exposure on circulating monocytes, we employed a THP-1 cell line based in vitro model. Flow cytometry and Western blot analyses were subsequently applied. Hemin-treated THP-1 produced ROS in a dose-dependent manner which resulted in 10-30 % of cell death primarily through apoptosis. Surviving cells induced autophagy which too was ROS-dependent, as revealed by application of N-acetyl-L-cysteine. Hemin-mediated autophagy promoted differentiation of CD14+ THP-1 cells into CD11b+ macrophages. Application of 3-methyladenine, reinforced that differentiation of THP-1 was an autophagy-dependent process. It was revealed that despite a higher polarization towards M2-macrophage, synthesis of pro-inflammatory cytokines namely TNF-α, IL-1A, IL-2, IL-8 and IL-17A predominated. IL-6, a pleiotropic cytokine, was also elevated. It may thus be surmised that hemin-induced pro-inflammatory response in THP-1 is downstream to ROS-dependent autophagy and monocyte differentiation. This finding is translationally meaningful as hemin is already approved by FDA for amelioration of acute porphyria and is actively considered as a therapeutic agent for other diseases. This study underscores the need of further research untangling the reciprocal regulation of inflammatory signaling and autophagy under oxidative stress.

Transfusion support and pre-transfusion testing in autoimmune haemolytic anaemia

Autoimmune haemolytic anaemia (AIHA) is characterized by an increased destruction of red blood cells due to immune dysfunction and auto-antibody production. Clinical manifestations are mainly related to anaemia, which can become life-threatening in case of acute haemolysis. Aiming at counterbalancing severe anaemia, supportive treatments for these patients frequently include transfusions. Unfortunately, free serum auto-antibodies greatly interfere in pre-transfusion testing, and the identification of compatible red blood cell units for AIHA patients can be challenging or even impossible. Problems faced in pre-transfusion testing often lead to delay or abandonment of transfusions for AIHA patients. In this review, we discuss publications concerning global transfusion management in AIHA, with a focus on pre-transfusion testing, and practical clues to manage the selection of transfusion units for these patients. Depending on the degree of transfusion emergency, we propose an algorithm for the selection and laboratory testing of units to be transfused to AIHA patients.

Organizing Pneumonia in a Case of Cold Agglutinin Disease with Pulmonary Thrombosis

Cold agglutinin disease is a subtype of autoimmune hemolytic anemia that occurs via the activation of specific anti-red blood cell antibodies (agglutinins) at low temperatures. Autoimmune hemolytic anemia has been reported to cause interstitial pneumonia; however, the underlying mechanism remains unclear. We herein report a 46-year-old man diagnosed with cold agglutinin disease complicated by pulmonary thrombosis and organizing pneumonia. Treatment with prednisolone improved the course of cold agglutinin disease and organizing pneumonia in a similar manner. To our knowledge, this is the first report of cold agglutinin associated with organizing pneumonia, suggesting a potential link between the two.

Clinical and laboratory profile of patients with positive direct antiglobulin test attended at a university hospital in Goias, Brazil

OBJECTIVE

To clinically and laboratory characterize patients with a positive direct antiglobulin test (DAT) treated at the Hospital das Clínicas of the Federal University of Goiás (HC-UFG).

METHODS

A retrospective, descriptive, cross-sectional study was carried out collecting data from medical records of patients with a positive DAT who were treated at HC-UFG between August 2021 and August 2022.

RESULTS

Eighty-four patients with positive polyspecific DAT results were screened in the clinical laboratory. Fifty-four patients had a laboratory profile compatible with autoimmune hemolytic anemia (AIHA), however, among these, 16 patients already had a diagnosis of AIHA in their medical records. The most common symptoms present among AIHA patients were pallor, asthenia, fatigue and dyspnea. For the remaining patients, the most common symptoms were severe thrombocytopenia, anemia, renal dysfunction, fever, myalgia, headache, thrombosis, asthenia, hematuria and joint pain. Only one patient had primary AIHA, that is, he had no evident underlying disease. The majority of AIHA patients (75 %) underwent corticosteroid therapy with 60 % having a positive response. For patients without AIHA, prednisone was the most frequently prescribed medication in 17 (25 %) patients, followed by hydroxychloroquine (14 patients - 20.1 %).

CONCLUSION

It is essential to evaluate patients with positive DAT in detail in order to understand the real clinical case. The DAT serological result alone does not arrive at a conclusive diagnosis of AIHA, and so it must be evaluated in conjunction with both clinical data and other laboratory tests, such as hemoglobin concentration and hemolysis tests (reticulocytes, lactate dehydrogenase and/or haptoglobin).

Recombinant erythropoietin in autoimmune hemolytic anemia with inadequate bone marrow response: a prospective analysis

ABSTRACT

Up to 30% of patients with autoimmune hemolytic anemia (AIHA) show inadequate bone marrow (BM) compensatory response with inappropriately low levels of reticulocytes and endogenous erythropoietin. Ineffective BM compensation is associated with more severe anemia, transfusion need, and hospital admission, and treatment with recombinant erythropoietin (rEPO) may be beneficial. Here, we prospectively analyzed the efficacy and safety of rEPO in a single-center cohort of 47 patients with AIHA with inadequate reticulocytosis and endogenous erythropoietin at baseline. Epoetin alpha 40 000 international units per week were administered subcutaneously until hemoglobin (Hb) >11 g/dL and then tapered off. Overall response was 55% at 15 days, 74% at 1 month, 74% at 3 months, 80% at 6 months, and 91% at 12 months. Consistently, Hb values significantly increased from baseline to each subsequent time point (P<.001) with a median increase of +1.4, +2.4, +3.4, +3.8, and +4.4 g/dL, respectively. Transfusion needs reduced from 30% to <10% at 15 days and thereafter (P < .001). Concomitant medications included prednisone or methylprednisolone (N = 40, stable since >2 weeks from enrollment), mycophenolate mofetil (N = 1, ongoing since >3 months from enrollment), and rituximab (N = 7 patients with cold agglutinin disease from day 8). No association between concomitant medications and response to rEPO was found. Treatment was generally safe without rEPO-related severe adverse events. The comparison with an AIHA population not treated with rEPO showed a significant benefit of rEPO at 15 days and 1 month on response and Hb increase. These data support the use of rEPO as an add on to standard immunosuppression in AIHA with inadequate BM compensation. This trial was registered at www.clinicaltrials.gov as #NCT05931718.

Primary autoimmune haemolytic anaemia is associated with increased risk of ischaemic stroke: A binational cohort study from Denmark and France

Primary autoimmune haemolytic anaemia (AIHA) causes the destruction of red blood cells and a subsequent pro-thrombotic state, potentially increasing the risk of ischaemic stroke. We investigated the risk of ischaemic stroke in patients with AIHA in a binational study. We used prospectively collected data from nationwide registers in Denmark and France to identify cohorts of patients with primary AIHA and age- and sex-matched general population comparators. We followed the patient and comparison cohorts for up to 5 years, with the first hospitalization of a stroke during follow-up as the main outcome. We estimated cumulative incidence, cause-specific hazard ratios (csHR) and adjusted for comorbidity and exposure to selected medications. The combined AIHA cohorts from both countries comprised 5994 patients and the 81 525 comparators. There were 130 ischaemic strokes in the AIHA cohort and 1821 among the comparators. Country-specific estimates were comparable, and the overall adjusted csHR was 1.36 [95% CI: 1.13-1.65], p = 0.001; the higher rate was limited to the first year after AIHA diagnosis (csHR 2.29 [95% CI: 1.77-2.97], p < 10-9 ) and decreased thereafter (csHR 0.89 [95% CI: 0.66-1.20], p = 0.45) (p-interaction < 10-5 ). The findings indicate that patients diagnosed with primary AIHA are at higher risk of ischaemic stroke in the first year after diagnosis.

Fostamatinib for warm antibody autoimmune hemolytic anemia: Phase 3, randomized, double-blind, placebo-controlled, global study (FORWARD)

Warm antibody autoimmune hemolytic anemia (wAIHA) is characterized by hemolysis and symptomatic anemia with no approved treatment options. Fostamatinib is an oral spleen tyrosine kinase inhibitor approved in the US and Europe for treatment of adults with chronic immune thrombocytopenia. In this phase 3 study, patients with an insufficient response to ≥1 prior wAIHA treatment were randomized to fostamatinib or placebo. The primary endpoint was the proportion of patients to achieve a durable hemoglobin (Hgb) response (Hgb ≥10 g/dL and increase from baseline of ≥2 g/dL on 3 consecutive visits) during the 24-week treatment period. Ninety patients were randomized, 45 to each arm. Of the fostamatinib-treated patients, 35.6% achieved a durable Hgb response versus 26.7% on placebo (p = .398). A post hoc analysis revealed a large placebo response in Eastern European patients. Significantly more patients on fostamatinib from North America, Australia and Western Europe exhibited a durable Hgb response compared to placebo (36% vs. 10.7%, p = .030). After censoring for Hgb values impacted by steroid rescue received during screening and excluding 2 placebo patients found to likely not have wAIHA, a reanalysis demonstrated a difference in durable Hgb response between fostamatinib and placebo (15/45 [33.3%] vs. 6/43 [14.0%], p = .0395). At least 1 AE was reported in 42 (93.3%) and 40 (88.9%) patients receiving fostamatinib and placebo, respectively. The most common AEs in the fostamatinib group were diarrhea (26.7%), hypertension (24.4%), and fatigue (15.6%). In this study, fostamatinib demonstrated a clinically meaningful benefit for patients in Western regions, and no new safety signals were identified.

Antiplasmodial and interferon-gamma-modulating activities of the aqueous extract of stone breaker (Phyllanthus niruri Linn.) in malaria infection

Plasmodium falciparum parasites are the primary cause of malaria across Africa. The problem of drug resistance to malaria is ever growing and novel therapeutic strategies need to be developed, particularly those targeting the parasite and also the host or host-pathogen interaction. Previous studies have shown that the development of cerebral malaria (CM) is related to dysregulation of the immune system in a murine malaria model of experimental cerebral malaria. It involves a complex interaction of events and interferon-gamma seems to be the unifying factor. Therefore, the antiplasmodial activity targeting the parasite and immunomodulatory strategies that reduce overall host inflammation, with IFN-γ in focus, could delay CM onset and prove beneficial in malaria infection therapy. Phyllanthus niruri is used to treat fever and other symptoms of malaria in Nigeria. Its modes of action as an anti-malarial remedy have not been exhaustively investigated. This study therefore examined the aqueous extract of P. niruri (PE) for its antiplasmodial activity in vitro using the Plasmodium falciparum HB3 strain. Furthermore, in vivo murine malaria model using the Plasmodium berghei ANKA strain was used to investigate its anti-malarial effects. We showed that PE has multiple anti-malarial effects, including anti-parasitic and host immunomodulatory activities. Co-culture of P. falciparum with PE and some of its phytoconstituents drastically reduced parasite number. PE also decreased parasitemia, and increased the survival of infected mice. We also observed that the integrity of the blood-brain barrier was maintained in the PE-treated mice. The results confirmed that PE showed moderate antiplasmodial activity. In vivo murine malaria model using P. berghei ANKA for experimental cerebral malaria revealed that PE suppressed parasite growth, and modulate the production of interferon-gamma. The findings demonstrate that PE affects malaria progression, targeting parasites and host cells.

Sirolimus is effective for primary refractory/relapsed warm autoimmune haemolytic anaemia/Evans syndrome: a retrospective single-center study

BACKGROUND

Some patients with warm autoimmune haemolytic anaemia (wAIHA) or Evans syndrome (ES) have no response to glucocorticoid or relapse. Recent studies found that sirolimus was effective in autoimmune cytopenia with a low relapse rate.

METHODS

Data from patients with refractory/relapsed wAIHA and ES in Peking Union Medical College Hospital from July 2016 to May 2022 who had been treated with sirolimus for at least 6 months and followed up for at least 12 months were collected retrospectively. Baseline and follow-up clinical data were recorded and the rate of complete response (CR), partial response (PR) at different time points, adverse events, relapse, outcomes, and factors that may affect the efficacy and relapse were analyzed.

RESULTS

There were 44 patients enrolled, with 9 (20.5%) males and a median age of 44 (range: 18-86) years. 37 (84.1%) patients were diagnosed as wAIHA, and 7 (15.9%) as ES. Patients were treated with sirolimus for a median of 23 (range: 6-80) months and followed up for a median of 25 (range: 12-80) months. 35 (79.5%) patients responded to sirolimus, and 25 (56.8%) patients achieved an optimal response of CR. Mucositis (11.4%), infection (9.1%), and alanine aminotransferase elevation (9.1%) were the most common adverse events. 5/35 patients (14.3%) relapsed at a median of 19 (range: 15-50) months. Patients with a higher sirolimus plasma trough concentration had a higher overall response (OR) and CR rate (p = 0.009, 0.011, respectively). At the time of enrolment, patients were divided into two subgroups that relapsed or refractory to glucocorticoid, and the former had poorer relapse-free survival (p = 0.032) than the other group.

CONCLUSION

Sirolimus is effective for patients with primary refractory/relapsed wAIHA and ES, with a low relapse rate and mild side effects. Patients with a higher sirolimus plasma trough concentration had a higher OR and CR rate, and patients who relapsed to glucocorticoid treatment had poorer relapse-free survival than those who were refractory.

Autoimmune Haemolytic Anaemia as a Rare and Potentially Serious Complication of Crohn's Disease in a 11-Year-Old Child-Case Report and Minireview

Inflammatory bowel disease (IBD) is the term given to a heterogeneous group of chronic inflammatory diseases of the gastrointestinal tract (GI). These include ulcerative colitis (UC), where the inflammatory process involves only the intestinal mucosa, and Crohn's disease (CD), where it can involve the entire wall of the GI in all of its sections. In addition to typical gastrointestinal complaints, IBD manifests with a range of extraintestinal symptoms involving inter alia the eyes, joints, skin, liver and biliary tract. These can cause a number of extraintestinal complications; of these, one of the most common is anaemia, usually resulting from nutritional deficiencies, especially iron, or chronic inflammation. When treating patients with IBD, it is important to consider the possibility of rare but serious complications, including autoimmune haemolytic anaemia (AIHA). This condition occurs in only 0.2 to 1.7% of UC cases and is even rarer in CD. AIHA is usually mild but can occur suddenly and cause very rapid anaemia. In the article presented here, we describe the case of a patient who developed AIHA two years after a diagnosis of CD, causing a life-threatening diagnostic and therapeutic challenge for the medical team.

Immune-mediated hematological disease in dogs is associated with alterations of the fecal microbiota: a pilot study

BACKGROUND

The dog is the most popular companion animal and is a valuable large animal model for several human diseases. Canine immune-mediated hematological diseases, including immune-mediated hemolytic anemia (IMHA) and immune thrombocytopenia (ITP), share many features in common with autoimmune hematological diseases of humans. The gut microbiome has been linked to systemic illness, but few studies have evaluated its association with immune-mediated hematological disease. To address this knowledge gap, 16S rRNA gene sequencing was used to profile the fecal microbiota of dogs with spontaneous IMHA and ITP at presentation and following successful treatment. In total, 21 affected and 13 healthy control dogs were included in the study.

RESULTS

IMHA/ITP is associated with remodeling of fecal microbiota, marked by decreased relative abundance of the spirochete Treponema spp., increased relative abundance of the pathobionts Clostridium septicum and Escherichia coli, and increased overall microbial diversity. Logistic regression analysis demonstrated that Treponema spp. were associated with decreased risk of IMHA/ITP (odds ratio [OR] 0.24-0.34), while Ruminococcaceae UCG-009 and Christensenellaceae R-7 group were associated with increased risk of disease (OR = 6.84 [95% CI 2-32.74] and 8.36 [95% CI 1.85-71.88] respectively).

CONCLUSIONS

This study demonstrates an association of immune-mediated hematological diseases in dogs with fecal dysbiosis, and points to specific bacterial genera as biomarkers of disease. Microbes identified as positive or negative risk factors for IMHA/ITP represent an area for future research as potential targets for new diagnostic assays and/or therapeutic applications.

Case report: Autoimmune hemolytic anemia caused by warm and cold autoantibodies with complement activation-etiological and therapeutic issues

Introduction

Research on mixed warm and cold autoantibodies in autoimmune hemolytic anemia (AIHA) targeting erythrocytes [red blood cells (RBCs)] and platelets is scarcely reported.

Case presentation

In this study, we present the case of a 5-year-old boy with positive direct [anti-IgG (1+), anti-IgG-C3d (3+)], and indirect antiglobulin (Coombs) tests. The RBCs were coated with polyspecific-positive, warm IgG autoantibodies alongside activated complement components. Plasma-containing immunoglobulin M (IgM) class autoantibodies were found in 1:64 titers with a wide temperature range of 4°C-37°C. The platelets were also coated with IgM autoantibodies. There was a reduction in the levels of the classical and alternative complement pathways, such as C3, C4, ADAMTS13 metalloprotease activity, factor H antigen, complement factor B antigen, and C1q antigen alongside the elevated sC5b-9 terminal complement complex. Hematuria and/or proteinuria, reduced diuresis, and elevated levels of serum creatinine were absent. The kidney ultrasound report was normal. A recent combination of Epstein-Barr virus (EBV) and cytomegalovirus (CMV) infection was found. The first-line treatment consisted of intravenous methylprednisolone [4 mg/kg/body weight for the first 72 h (q12 h), followed by 2 mg/kg body weight for 21 consecutive days with a slow steroid reduction until plasmapheresis (PLEX)]. After the patient showed limited response to corticosteroid therapy, rituximab (375 mg/m2) was administered once a week (five doses in total), with vitamins B9 and B12. These strategies also showed limited (partial) therapeutic benefits. Therefore, the treatment was switched to PLEX (five cycles in total) and intravenous immunoglobulin (IVIg) (1 g/kg/5 days). This combination significantly improved RBC count and platelet levels, and C3 and C4 levels returned to normal. A follow-up of 2.5 years after treatment showed no sign of relapse. A genetic analysis revealed a rare heterozygous intronic variation (c.600-14C > T) and heterozygous Y402H polymorphism of the CFH gene. c.600-14C > T mutation was located near the 5' end of exon 6 in the gene encoding the complement C3 protein of unknown significance. We presumed that the complement regulators in our patient were sufficient to control complement activation and that complement blockade should be reserved only for devastating, life-threatening complement-related multiorgan failure.

Conclusion

We believe that EBV and CMV triggered AIHA, thus activating the complement cascade. Hence, we used corticosteroids, rituximab, vitamins B9 + B12, PLEX, and fresh frozen plasma (FFP) as treatment. Final remission was achieved with PLEX and FFP. However, an additional late effect of B12 rituximab and the disappearance of long-lived circulating plasma cells should not be completely ignored. Complement activation with a genetic background should be assessed in severe warm and cold hemolytic anemias caused by autoantibodies.

The Role of the Spleen and the Place of Splenectomy in Autoimmune Hemolytic Anemia-A Review of Current Knowledge

Autoimmune hemolytic anemia (AIHA) is a rare, very heterogeneous, and sometimes life-threatening acquired hematologic disease characterized by increased red blood cell (RBC) destruction by autoantibodies (autoAbs), either with or without complement involvement. Recent studies have shown that the involvement of T- and B-cell dysregulation and an imbalance of T-helper 2 (Th2) and Th17 phenotypes play major roles in the pathogenesis of AIHA. AIHA can be primary (idiopathic) but is more often secondary, triggered by infections or drug use or as a part of other diseases. As the location of origin of autoAbs and the location of autoAb-mediated RBC clearance, as well as the location of extramedullary hematopoiesis, the spleen is crucially involved in all the steps of AIHA pathobiology. Splenectomy, which was the established second-line therapeutic option in corticosteroid-resistant AIHA patients for decades, has become less common due to increasing knowledge of immunopathogenesis and the introduction of targeted therapy. This article provides a comprehensive overview of current knowledge regarding the place of the spleen in the immunological background of AIHA and the rapidly growing spectrum of novel therapeutic approaches. Furthermore, this review emphasizes the still-existing expediency of laparoscopic splenectomy with appropriate perioperative thromboprophylaxis and the prevention of infection as a safe and reliable therapeutic option in the context of the limited availability of rituximab and other novel therapies.

Metaxalone-induced Immune Hemolytic Anemia

Drug-induced immune hemolytic anemia (DIIHA) is a relatively uncommon cause of anemia, and its diagnosis can be challenging. Although beta-lactam antimicrobial agents are often associated with DIIHA, any medication can potentially cause it. We describe a patient presenting with yellow skin discoloration and orange-colored urine after starting metaxalone for treatment of lumbosacral sprain. Laboratory studies were consistent with warm hemolytic anemia. Symptoms improved remarkably after discontinuation of metaxalone, coupled with initiation of glucocorticoids and rituximab.

C1-inhibitor treatment in patients with severe complement-mediated autoimmune hemolytic anemia

Complement-mediated (CM) autoimmune hemolytic anemia (AIHA) is characterized by the destruction of red blood cells (RBCs) by autoantibodies that activate the classical complement pathway. These antibodies also reduce transfusion efficacy via the lysis of donor RBCs. Because C1-inhibitor (C1-INH) is an endogenous regulator of the classical complement pathway, we hypothesized that peritransfusional C1-INH in patients with severe CM-AIHA reduces complement activation and hemolysis, and thus enhances RBC transfusion efficacy. We conducted a prospective, single-center, phase 2, open-label trial (EudraCT2012-003710-13). Patients with confirmed CM-AIHA and indication for the transfusion of 2 RBC units were eligible for inclusion. Four IV C1-INH doses (6000, 3000, 2000, and 1000 U) were administered with 12-hour intervals around RBC transfusion. Serial blood samples were analyzed for hemolytic activity, RBC opsonization, complement activation, and inflammation markers. Ten patients were included in the study. C1-INH administration increased plasma C1-INH antigen and activity, peaking at 48 hours after the first dose and accompanied by a significant reduction of RBC C3d deposition. Hemoglobin levels increased briefly after transfusion but returned to baseline within 48 hours. Overall, markers of hemolysis, inflammation, and complement activation remained unchanged. Five grade 3 and 1 grade 4 adverse event occurred but were considered unrelated to the study medication. In conclusion, peritransfusional C1-INH temporarily reduced complement activation. However, C1-INH failed to halt hemolytic activity in severe transfusion-dependent-CM-AIHA. We cannot exclude that posttransfusional hemolytic activity would have been even higher without C1-INH. The potential of complement inhibition on transfusion efficacy in severe CM-AIHA remains to be determined.

Ultrastructural analysis of nucleated erythrocyte in patients with autoimmune hemolytic anemia (AIHA)

Autoimmune hemolytic anemia (AIHA) is a group of diseases characterized by immune-mediated lysis of mature red blood cells (RBCs). It is mainly classified into primary and secondary types based on etiology and mechanisms underlying autoantibody production. AIHA is diagnosed using morphological observation of bone marrow smears under a light microscope and monospecific direct antiglobulin test to detect hemolysis. Here, we retrospectively studied ultrastructural abnormalities of nucleated erythroid cells in bone marrows from 10 patients with AIHA using transmission electron microscopy. Our results revealed severe damage and injury to nucleated erythroid cells, including morphological irregularity, pyknosis, karyolysis, expansion of perinuclear cisternae and cytoplasmic lysis. These results indicate that aberrant immunity attacks not only mature RBCs but also nucleated erythroid cells, and ineffective hematopoiesis is partly involved in the pathogenesis of AIHA.

Molecular Mechanisms and Pathophysiological Significance of Eryptosis

Despite lacking the central apoptotic machinery, senescent or damaged RBCs can undergo an unusual apoptosis-like cell death, termed eryptosis. This premature death can be caused by, or a symptom of, a wide range of diseases. However, various adverse conditions, xenobiotics, and endogenous mediators have also been recognized as triggers and inhibitors of eryptosis. Eukaryotic RBCs are unique among their cell membrane distribution of phospholipids. The change in the RBC membrane composition of the outer leaflet occurs in a variety of diseases, including sickle cell disease, renal diseases, leukemia, Parkinson’s disease, and diabetes. Eryptotic erythrocytes exhibit various morphological alterations such as shrinkage, swelling, and increased granulation. Biochemical changes include cytosolic Ca2+ increase, oxidative stress, stimulation of caspases, metabolic exhaustion, and ceramide accumulation. Eryptosis is an effective mechanism for the elimination of dysfunctional erythrocytes due to senescence, infection, or injury to prevent hemolysis. Nevertheless, excessive eryptosis is associated with multiple pathologies, most notably anemia, abnormal microcirculation, and prothrombotic risk; all of which contribute to the pathogenesis of several diseases. In this review, we provide an overview of the molecular mechanisms, physiological and pathophysiological relevance of eryptosis, as well as the potential role of natural and synthetic compounds in modulating RBC survival and death.

T-cell senescence: A crucial player in autoimmune diseases

Senescent T cells are proliferative disabled lymphocytes that lack antigen-specific responses. The development of T-cell senescence in autoimmune diseases contributes to immunological disorders and disease progression. Senescent T cells lack costimulatory markers with the reduction of T cell receptor repertoire and the uptake of natural killer cell receptors. Senescent T cells exert cytotoxic effects through the expression of perforin, granzymes, tumor necrosis factor, and other molecules without the antigen-presenting process. DNA damage accumulation, telomere damage, and limited DNA repair capacity are important features of senescent T cells. Impaired mitochondrial function and accumulation of reactive oxygen species contribute to T cell senescence. Alleviation of T-cell senescence could provide potential targets for the treatment of autoimmune diseases.

Three different pathways of IgM-antibody-dependent hemolysis are mainly regulated by complement

Antibodies to red blood cells (RBCs) may hemolyze erythrocytes via Fc-mediated phagocytosis or complement-dependent. Complement activation on RBCs can be detected by C3d-direct antiglobulin test (DAT), which is the only test in immune hematology that directly targets complement. However, a positive DAT with anti-C3d cannot distinguish between C3b-mediated extravascular hemolysis, C5b-C9-mediated intravascular hemolysis and C5b-C8-mediated eryptosis. Furthermore, DAT is not suitable to estimate the strength of hemolysis. Autoimmune hemolytic anemia (AIHA) is a rare disease that is caused by autoantibodies to red blood cells that is divided in warm AIHA and in cold agglutinin disease (CAD). The causative antibodies in CAD and sometimes in warm AIHA are from the IgM class. Depending on strength of complement activation they can induce extravascular hemolysis, intravascular hemolysis and eryptosis. We studied the three types of hemolysis by use of sera from patients with CAD under various conditions. We found that additionally to the routinely applied C3d-DAT, indirect tests for complement activity (free hemoglobin and Annexin V-binding to phosphatidylserine-exposing RBCs) should be used to determine the portion of extravascular, intravascular and eryptotic hemolysis. Eryptotic hemolysis may have a significant share in clinical relevant CAD or IgM warm AIHA, which should be considered for successful treatment.

Metabolomic profile in patients with primary warm autoimmune haemolytic anaemia

Autoimmune haemolytic anaemia (AIHA) is a rare clinical condition with immunoglobulin fixation on the surface of erythrocytes, with or without complement activation. The pathophysiology of AIHA is complex and multifactorial, presenting functional abnormalities of T and B lymphocytes that generate an imbalance between lymphocyte activation, immunotolerance and cytokine production that culminates in autoimmune haemolysis. In AIHA, further laboratory data are needed to predict relapse and refractoriness of therapy, and thus, prevent adverse side-effects and treatment-induced toxicity. The metabolomic profile of AIHA has not yet been described. Our group developed a cross-sectional study with follow-up to assess the metabolomic profile in these patients, as well as to compare the metabolites found depending on the activity and intensity of haemolysis. We analysed the plasma of 26 patients with primary warm AIHA compared to 150 healthy individuals by mass spectrometry. Of the 95 metabolites found in the patients with AIHA, four acylcarnitines, two phosphatidylcholines (PC), asymmetric dimethylarginine (ADMA) and three sphingomyelins were significantly increased. There was an increase in PC, spermine and spermidine in the AIHA group with haemolytic activity. The PC ae 34:3/PC ae 40:2 ratio, seen only in the 12-month relapse group, was a predictor of relapse with 81% specificity and 100% sensitivity. Increased sphingomyelin, ADMA, PC and polyamines in patients with warm AIHA can interfere in autoantigen and autoimmune recognition mechanisms in a number of ways (deficient action of regulatory T lymphocytes on erythrocyte recognition as self, negative regulation of macrophage nuclear factor kappa beta activity, perpetuation of effector T lymphocyte and antibody production against erythrocyte antigens). The presence of PC ae 34:3/PC ae 40:2 ratio as a relapse predictor can help in identifying cases that require more frequent follow-up or early second-line therapies.

Case report: Successful outcome of treatment using rituximab in an adult patient with refractory minimal change disease and β-thalassemia complicating autoimmune hemolytic anemia

Minimal change disease (MCD) is one of the common causes of idiopathic nephrotic syndrome (INS), accounting for 10-20% of INS in adults. Glucocorticoids are the most commonly used and effective drugs in the treatment of MCD, but there is still a proportion of adult patients with MCD who are characterized by glucocorticoid resistance, glucocorticoid dependence, and frequent relapse, which are defined as refractory nephrotic syndrome. Glucocorticoid combination with immunosuppressants is frequently used in patients with refractory nephrotic syndrome, and patients concerned about adverse effects caused by long-term high-dose glucocorticoid therapy. Recent studies have suggested that Rituximab (RTX), a chimeric monoclonal antibody targeted against the pan-B-cell marker CD20, combined with a small or medium dose of glucocorticoid has a beneficial effect with less adverse effects on adult patients with refractory MCD. β-thalassemia is an inherited hemoglobulin disorder caused by the mutation of genes that encode β-globin and results in ineffective erythropoiesis. We here report a case of an adult patient with refractory MCD complicated with β-thalassemia minor accompanied by autoimmune hemolytic anemia (AIHA). MCD relapsed several times despite treatment using glucocorticoid combined with or without different immunosuppressive agent regimens. The β-thalassemia minor was caused by heterozygosity for a 4-base deletion mutation [codons 41/42 (-TTCT) BETA0] of the β-globin gene. After the administration of RTX, MCD achieved clinical complete remission, and the anemia due to mild β-thalassemia recovered to normal as well. The disease situation remained stable during 36 months of follow-up. These findings suggest that RTX may contribute to the improvement of refractory MCD and anemia in β-thalassemia minor accompanied by AIHA.

Severe refractory warm autoimmune haemolytic anaemia after the SARS-CoV-2 Pfizer-BioNTech vaccine (BNT162b2 mRNA) managed with emergency splenectomy and complement inhibition with eculizumab

A male in his teens with a history of liver transplant for biliary atresia (aged 2 years) and autoimmune haemolytic anaemia (AIHA, aged 6 years) presented with jaundice, dark urine, fatigue and chest discomfort that began 48 hours after the first dose of SARS-CoV-2 Pfizer-BioNTech vaccine (BNT162b2 mRNA). Investigations revealed a warm AIHA picture. Over 4 weeks the patient developed life-threatening anaemia culminating in haemoglobin of 35 g/L (after transfusion), lactate dehydrogenase of 1293 units/L and bilirubin of 228 µmol/L, refractory to standard treatment with corticosteroids and rituximab. An emergency splenectomy was performed that slowed haemolysis but did not completely ameliorate it. Eculizumab, a terminal complement pathway inhibitor, was initiated to arrest intravascular haemolysis and showed a favourable response. AIHA is rare but described after the SARS-CoV-2 Pfizer-BioNTech vaccine. This case highlights the rare complication of AIHA, the use of emergency splenectomy for disease control, and the use of eculizumab.

Methods to Evaluate the Potential Clinical Significance of Antibodies to Red Blood Cells

Immune-mediated red blood cell (RBC) destruction due to antibodies is an ongoing problem in transfusion medicine for the selection of the safest blood. Serological testing often revealed incompatibility with donors' RBCs. When this incompatible blood was transfused, destruction was due mostly to extravascular-mediated phagocytosis of the antibody-opsonized RBCs; however, intravascular hemolysis was sometimes observed without explanation. Based on serology, antibodies with potential for clinical sequalae could not be ascertained; thus, antigen-negative blood was usually selected for transfusion to avoid problems. Antibodies to antigens having very high frequency in the general population (>95%), however, made selection of antigen-negative blood difficult and sometimes impossible. Some patients, who were sensitized by previous transfusions or by pregnancy, developed multiple antibodies, again creating a problem for finding compatible blood for transfusion, without the ability to discern which of the antibodies may be clinically irrelevant and ignored. Transfusion medicine scientists began searching for an in vitro means to determine the in vivo outcome of transfusion of blood that was serologically incompatible. Methods such as chemiluminescence, monocyte-macrophage phagocytosis, and antibody-dependent cellular cytotoxicity (ADCC) were described. Over the years, the monocyte monolayer assay (MMA) has emerged as the most reliable in vitro assay for the prediction of the clinical relevance of a given antibody. ADCC has not been fully studied but has the potential to be useful for predicting which antibodies may result in intravascular hemolysis. This article captures the protocols for the implementation and readout of the MMA and ADCC assays for use in predicting the clinical significance of antibodies in a transfusion setting. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Monocyte monolayer assay (MMA) Basic Protocol 2: Antibody-dependent cellular cytotoxicity assay (ADCC).

A Case of Warm Autoimmune Hemolytic Anemia Secondary to Epstein-Barr Virus Infection

Autoimmune hemolytic anemia (AIHA) is a rare disease characterized by autoantibodies directed at red blood cells. Patients typically present with anemia and are diagnosed by positive direct antiglobulin (DAT) test. AIHA is subclassified into warm or cold based on antibodies involved and depending on their optimal temperature in which they react with RBC antigens. Warm AIHA can be either primary (idiopathic) or secondary depending on etiology. Secondary causes are associated with malignancy, connective tissue and inflammatory diseases, infections (typically viral infections), or drugs (e.g., antibiotics, chemotherapeutic agents). Epstein-Barr virus (EBV) is a herpes virus that is commonly associated with cold AIHA, with only one reported case of EBV-induced warm AIHA. It has been postulated that antibodies against EBV cross-react with antigens expressed on RBC membranes and activate the complement cascade similarly. This case report describes a case of a 32-year-old male who presented with warm AIHA secondary to EBV reinfection.

A Rare Case of COVID-19 Associated With Autoimmune Hemolytic Anemia, Thrombocytopenia and Acute Kidney Injury

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has numerous effects on different systemic organs other than the lungs. In this case report, we look at the presentation of a young female who was diagnosed with autoimmune hemolytic anemia (AIHA), kidney injury and thrombocytopenia during coronavirus disease 2019 (COVID-19) infection. She recovered well without the need for steroids. As demonstrated by this case, COVID-19 infection can be associated with the development of AIHA. The purpose of this report is to indicate that COVID-19 can present unusually with different clinical manifestations enough to require hospitalization.

COVID-19 and Immune-Mediated RBC Destruction

OBJECTIVES

To summarize the epidemiologic, clinical, and laboratory characteristics of autoimmune hemolytic anemia (AIHA) secondary to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or vaccination.

METHODS

We conducted a systematic review using standardized keyword search to identify all reports of SARS-CoV-2 infection or vaccination and AIHA across PubMed, Web of Science, Scopus, and Google Scholar through September 24, 2021.

RESULTS

Fifty patients (mean [SD] age, 50.8 [21.6] years) diagnosed with coronavirus disease 2019 (COVID-19) and AIHA were identified. AIHA subtypes and number of patients were as follows: cold AIHA (n = 18), warm AIHA (n = 14), mixed-type AIHA (n = 3), direct antiglobulin test (DAT)-negative AIHA (n = 1), DAT-negative Evans syndrome (n = 1), Evans syndrome (n = 3), and subtype not reported (n = 10). Mean (SD) hemoglobin at AIHA diagnosis was 6.5 [2.8] g/dL (95% confidence interval, 5.7-7.3 g/dL). Median time from COVID-19 symptom onset to AIHA diagnosis was 7 days. In total, 19% (8/42) of patients with COVID-19-associated AIHA with reported outcomes were deceased. Four patients (mean [SD] age, 73.5 [16.9] years) developed AIHA following SARS-CoV-2 vaccination: Pfizer-BioNTech BNT162b2 vaccine (n = 2); Moderna mRNA-1273 vaccine (n = 1); undisclosed mRNA vaccine (n = 1). AIHA occurred after 1 dose in 3 patients (median, 5 days).

CONCLUSIONS

SARS-CoV-2 infection and vaccination are associated with multiple AIHA subtypes, beginning approximately 7 days after infectious symptoms and 5 days after vaccination.

Warm autoimmune haemolytic anaemia seen in association with primary sclerosing cholangitis in the setting of Klebsiella pneumoniae bacteraemia

Warm autoimmune haemolytic anaemia mediated by warm agglutinins is a rare and heterogeneous disease which can be idiopathic or secondary to an underlying disease. Primary sclerosing cholangitis is a chronic autoimmune cholangiopathy that is very rarely associated with haemolytic anaemia. Infections can also act as triggers for immune haemolytic anaemia. Here, we report a case of a woman in her 50s with a history of primary sclerosing cholangitis and a positive direct antiglobulin test with no evidence of haemolysis who developed overt warm autoimmune haemolytic anaemia in the setting of cholangitis and Klebsiella pneumoniae bacteraemia. She was treated conservatively with appropriate antibiotics and cautious red blood cell transfusion with complete resolution of haemolysis; immunosuppression was avoided given sepsis on presentation. This case highlights a rare association of warm immune haemolytic anaemia in the setting of K. pneumoniae bacteraemia and the role of a tailored treatment approach to treat this heterogeneous disease.

Immunotherapy-associated Autoimmune Hemolytic Anemia

Over the past decade, the role of immunotherapy treatment in cancer has expanded; specifically, indications for immune checkpoint inhibitors (ICI) have multiplied and are used as first-line therapy. ICIs include cytotoxic T-lymphocyte-associated protein 4 and programmed cell death protein 1 inhibitors, as monotherapies or in combination. Autoimmune hemolytic anemia (AIHA) has emerged as a rare yet serious immune-related adverse event in ICI use. This review describes diagnosis and management of immunotherapy related AIHA (ir-AIHA) including an algorithmic approach based on severity of anemia. Suggested mechanisms are discussed, guidance on ICI resumption provided and prognosis reviewed including risk of recurrence.

Updates on the Diagnosis and Management of Cold Autoimmune Hemolytic Anemia

Cold agglutinin disease represents a form of immune-mediated hemolytic anemia whereby an IgM protein either monoclonal or polyclonal deposits complement on the surface of the red blood cell. Once complement is deposited, the 3rd component of complement is recognized by receptors in the mononuclear phagocyte system resulting in spherocytic extravascular hemolysis. This results in a Coombs positive hemolytic anemia with the peripheral blood film showing agglutination. In many instances, the source is a clonal population of lymphoplasmacytic cells in the bone marrow producing a monoclonal IgM protein. Traditional and emerging therapies directed against the production of the IgM may have a positive effect on hemolytic anemia. Success in the management of cold agglutinin disease with rituximab, fludarabine, bortezomib, and bendamustine has all been reported. Recent studies have demonstrated that the blockade of complement with sutimlimab can stop the hemolysis without the use of systemic chemotherapy.

Iguratimod in treatment of primary Sjögren’s syndrome concomitant with autoimmune hemolytic anemia: A case report

BACKGROUND

Primary Sjögren's syndrome (pSS) concomitant with autoimmune hemolytic anemia (AIHA) but without eye and mouth dryness is exceedingly rare. Iguratimod (IGU) has been widely used in the treatment of pSS. However, there are few reports about the application of IGU in pSS concomitant with AIHA.

CASE SUMMARY

Here, we present the case of a patient with pSS concomitant with AIHA but without eye and mouth dryness. The patient was initially diagnosed with hyperplastic anemia and AIHA while pSS was missed, and was finally diagnosed with pSS concomitant with AIHA. The patient was treated with IGU along with prednisone and hydroxychloroquine, and her hemoglobin, reticulocytes and IgG returned to normal levels.

CONCLUSION

IGU was effective for and well tolerated by our patient with pSS concomitant with AIHA, and may be a promising therapy for the treatment of this disease.

Control of Blood Coagulation by Hemocompatible Material Surfaces-A Review

Hemocompatibility of biomaterials in contact with the blood of patients is a prerequisite for the short- and long-term applications of medical devices such as cardiovascular stents, artificial heart valves, ventricular assist devices, catheters, blood linings and extracorporeal devices such as artificial kidneys (hemodialysis), extracorporeal membrane oxygenation (ECMO) and cardiopulmonary bypass. Although lower blood compatibility of materials and devices can be handled with systemic anticoagulation, its side effects, such as an increased bleeding risk, make materials that have a better hemocompatibility highly desirable, particularly in long-term applications. This review provides a short overview on the basic mechanisms of blood coagulation including plasmatic coagulation and blood platelets, as well as the activation of the complement system. Furthermore, a survey on concepts for tailoring the blood response of biomaterials to improve the hemocompatibility of medical devices is given which covers different approaches that either inhibit interaction of material surfaces with blood components completely or control the response of the coagulation system, blood platelets and leukocytes.

A New Murine Model of Primary Autoimmune Hemolytic Anemia (AIHA)

Loss of humoral tolerance to red blood cells (RBCs) can lead to autoimmune hemolytic anemia (AIHA), a severe, and sometimes fatal disease. Patients with AIHA present with pallor, fatigue, decreased hematocrit, and splenomegaly. While secondary AIHA is associated with lymphoproliferative disorders, infections, and more recently, as an adverse event secondary to cancer immunotherapy, the etiology of primary AIHA is unknown. Several therapeutic strategies are available; however, there are currently no licensed treatments for AIHA and few therapeutics offer treatment-free durable remission. Moreover, supportive care with RBC transfusions can be challenging as most autoantibodies are directed against ubiquitous RBC antigens; thus, virtually all RBC donor units are incompatible. Given the severity of AIHA and the lack of treatment options, understanding the cellular and molecular mechanisms that facilitate the breakdown in tolerance would provide insight into new therapeutics. Herein, we report a new murine model of primary AIHA that reflects the biology observed in patients with primary AIHA. Production of anti-erythrocyte autoantibodies correlated with sex and age, and led to RBC antigen modulation, complement fixation, and anemia, as determined by decreased hematocrit and hemoglobin values and increased reticulocytes in peripheral blood. Moreover, autoantibody-producing animals developed splenomegaly, with altered splenic architecture characterized by expanded white pulp areas and nearly diminished red pulp areas. Additional analysis suggested that compensatory extramedullary erythropoiesis occurred as there were increased frequencies of RBC progenitors detectable in the spleen. No significant correlations between AIHA onset and inflammatory status or microbiome were observed. To our knowledge, this is the first report of a murine model that replicates observations made in humans with idiopathic AIHA. Thus, this is a tractable murine model of AIHA that can serve as a platform to identify key cellular and molecular pathways that are compromised, thereby leading to autoantibody formation, as well as testing new therapeutics and management strategies.

Autoimmune Hemolytic Anemia Exacerbation Associated With COVID-19 Infection and Markedly Elevated Inflammatory Markers

The association between previously diagnosed autoimmune hemolytic anemia and exacerbations due to coronavirus disease 2019 (COVID-19) infection is a rare phenomenon that is not well understood. In this case, we present a 68-year-old female with a past medical history significant for systemic lupus erythematosus (SLE), splenectomy, and autoimmune hemolytic anemia (AIHA) since childhood that had been very well controlled with only one previous exacerbation. This patient's chief complaint and clinical symptoms at admission were related to hemolytic anemia and not active COVID-19 infection. This case report reveals a possible association between the hyperinflammatory syndrome caused by COVID-19 and the exacerbation of previously well-controlled autoimmune diseases.

Anti-plasma cell treatment in refractory autoimmune hemolytic anemia in a child with multivisceral transplant

BACKGROUND

Warm-antibody AIHA is known to complicate solid organ (SOT) and HSCT, the disease maybe refractory to standard therapy. Immunosuppressive therapies as well as IVIG, and rituximab have been the main stay of treatment. Over the past decade, B-lymphocyte targeted, anti-CD-20 antibody has been recognized in the treatment of autoimmune diseases and utilized in AIHA. Bortezomib, a proteasome inhibitor that causes apoptosis of plasma cells, is an appealing targeted therapy in secondary AIHA and has demonstrated efficacy in HSCT patients. From our experience, we advocate for early targeted therapy that combines B cell with plasma cell depletion.

CASE REPORT

We describe a 4-year-old-girl with stage III neuroblastoma, complicated with intestinal necrosis needing multivisceral transplant developed warm AIHA 1-year after transplantation, and following an adenovirus infection. She received immunoglobulin therapy, rituximab, sirolimus, plasmapheresis, and long-term prednisolone with no sustained benefit while developing spinal fractures related to the latter therapy. She received bortezomib for intractable AIHA in combination with rituximab with no appreciable adverse effects. Three years later the child remains in remission with normal reticulocyte and recovered B cells. In the interim, she required chelation therapy for iron overload related to blood transfusion requirement during the treatment of AIHA.

CONCLUSION

We propose early targeted anti-plasma cell therapy with steroid burst, IVIG, rituximab, and possible plasmapheresis may reduce morbidity in secondary refractory w-AIHA.

Complement-mediated autoimmune haemolytic anaemia as an initial presentation of Legionnaires' disease

A 42-year-old diabetic man presented to the hospital with severe sepsis and multiorgan dysfunction. A probable respiratory source of sepsis was suspected because of suggestive clinical and radiological findings. He was critically ill and was therefore admitted to intensive care for further management including ventilatory support and renal replacement therapy. He was also found to have marked anaemia requiring multiple blood transfusions with clinical and laboratory evidence pointing towards severe haemolysis. Further workup for the aetiology of pneumonia established a diagnosis of Legionella by confirmatory tests namely legionella antigen in the urine and exponentially rising serum antibody titres. The cause for the severe haemolysis was found to be complement-mediated autoimmune haemolysis as determined by direct antiglobulin test positive for complement components C3 and negative for IgG. Such clinically significant autoimmune haemolysis as a presenting feature, rather than a late complication, has never before been reported in the literature.

A Case of Autoimmune Hemolytic Anemia Following COVID-19 Messenger Ribonucleic Acid Vaccination

Autoimmune hemolytic anemia (AIHA) is a condition characterized by the increased destruction of red blood cells (RBCs) mediated by anti-erythrocyte autoantibodies with or without complement activation. Its clinical presentation is heterogeneous, ranging from asymptomatic to severe forms with fatal outcomes, and it can be either idiopathic or secondary to a coexisting disorder. In this report, we present a case of a patient who suffered from acute and severe AIHA after receiving the second dose of the coronavirus disease 2019 (COVID-19) messenger ribonucleic acid (mRNA) vaccine.

A Fatal Case of Dengue-Associated Hemophagocytic Lymphohistiocytosis and Retroperitoneal Hematoma in a Patient With Autoimmune Hemolytic Anemia

Hemophagocytic lymphohistiocytosis (HLH) is a rare but potentially life-threatening complication of dengue infection which necessitates early diagnosis and treatment to improve patient outcomes. Severe dengue infection complicated by HLH may require interventions such as systemic corticosteroids, intravenous immunoglobulin, or chemotherapy. Here, we report a case of concurrent dengue-induced HLH and flare of underlying autoimmune hemolytic anemia (AIHA). The disease was refractory to treatment including corticosteroids and intravenous immunoglobulin. The course of illness was later complicated by dengue shock syndrome, severe liver dysfunction, and a large retroperitoneal hematoma. Unfortunately, the patient succumbed on day 10 of illness.

How I treat warm autoimmune hemolytic anemia

Warm autoimmune hemolytic anemia (wAIHA) is caused by increased erythrocyte destruction by immunoglobulin G (IgG) autoantibodies, with or without complement activation. Antibody-dependent cell-mediated cytotoxicity by macrophages/activated lymphocytes occurs in the lymphoid organs and spleen (extravascular hemolysis). The ability of the bone marrow (BM) to compensate determines clinical severity. The different pathogenic mechanisms, their complex interplay, and changes over time may explain wAIHA's great clinical heterogeneity and unpredictable course. The disease may be primary, drug induced, or associated with lymphoproliferative neoplasms, autoimmune and infectious diseases, immunodeficiencies, solid tumors, or transplants. Therapeutic interventions include steroids, splenectomy, immunosuppressants, and rituximab; the latter is increasingly used in steroid-refractory cases based on evidence from the literature and a few prospective trials. We present 5 patient case studies highlighting important issues: (1) the diagnosis and proper use of steroid therapy, (2) the concerns about the choice between rituximab and splenectomy in second-line treatment, (3) the need of periodical re-evaluation of the disease to assess the possible evolution of relapsed/refractory cases in myelodysplastic and BM failure syndromes, and (4) the difficulties in managing cases of severe/acute disease that are at high risk of relapse. Incorporating novel targeted therapies into clinical practice will be an exciting challenge in the future.

Immune cytopenia after allogeneic haematopoietic stem-cell transplantation: challenges, approaches, and future directions

Immune-mediated cytopenia after allogeneic haematopoietic stem-cell transplantation is rare. The pathophysiology of immune-mediated anaemia, thrombocytopenia, and neutropenia, which occur alone or in combination with other cytopenias, is unclear and most probably a consequence of immune dysregulation. Risk factors for this complication have been identified in retrospective studies but these should be interpreted with caution and should not be generalised to this heterogeneous patient population. Diagnosis is challenging, requires awareness of such complications, and has to be differentiated from a multitude of other, and sometimes overlapping, possible complications. The clinical course of immune-mediated cytopenia is highly variable. Treatment requires an interdisciplinary approach and ranges from observation to symptomatic measures and directed therapies. Intensive immunosuppression is associated with an increased risk of infections and relapse, and current treatments are based on approaches in patients who have not undergone transplantation. Plasma cell-directed therapies, immunomodulation, and receptor-stimulating agents can be used to treat immune-mediated cytopenia.

Diagnosis and Management of Autoimmune Hemolytic Anemia in Patients with Liver and Bowel Disorders

Anemia is a common feature of liver and bowel diseases. Although the main causes of anemia in these conditions are represented by gastrointestinal bleeding and iron deficiency, autoimmune hemolytic anemia should be considered in the differential diagnosis. Due to the epidemiological association, autoimmune hemolytic anemia should particularly be suspected in patients affected by inflammatory and autoimmune diseases, such as autoimmune or acute viral hepatitis, primary biliary cholangitis, and inflammatory bowel disease. In the presence of biochemical indices of hemolysis, the direct antiglobulin test can detect the presence of warm or cold reacting antibodies, allowing for a prompt treatment. Drug-induced, immune-mediated hemolytic anemia should be ruled out. On the other hand, the choice of treatment should consider possible adverse events related to the underlying conditions. Given the adverse impact of anemia on clinical outcomes, maintaining a high clinical suspicion to reach a prompt diagnosis is the key to establishing an adequate treatment.

Infectious Complications in Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemia (AIHA) may be frequently challenged by infectious complications, mainly as a result of immunosuppressive treatments administered. Furthermore, infectious agents are known triggers of AIHA onset and relapse. Although being risk factors for mortality, infections are an underestimated issue in AIHA. This review will collect the available evidence on the frequency and type of infectious complications in AIHA, detailing the risk related to each treatment (i.e., steroids, rituximab, splenectomy, classic immunosuppressive agents, and new target drugs). Moreover, we will briefly discuss the infectious complications in AIHA secondary to other diseases that harbor an intrinsic infectious risk (e.g., primary immunodeficiencies, systemic autoimmune diseases, lymphoproliferative disorders, solid organ and hematopoietic stem cell transplants). Finally, viral and bacterial reactivations during immune suppressive therapies will be discussed, along with suggested screening and prophylactic strategies.

Rituximab Use in Warm and Cold Autoimmune Hemolytic Anemia

Autoimmune hemolytic anemia is a rare condition characterized by destruction of red blood cells with and without involvement of complement. It is associated with significant morbidity and mortality. In warm autoimmune hemolytic anemia, less than 50% of patients remain in long-term remission following initial steroid therapy and subsequent therapies are required. Cold agglutinin disease is a clonal hematologic disorder that requires therapy in the majority of patients and responds poorly to steroids and alkylators. Rituximab has a favorable toxicity profile and has demonstrated efficacy in autoimmune hemolytic anemia in first-line as well as relapsed settings. Rituximab is the preferred therapy for steroid refractory warm autoimmune hemolytic anemia (wAIHA) and as part of the first- and second-line treatment of cold agglutinin disease. This article reviews the mechanism of action of rituximab and the current literature on its role in the management of primary and secondary warm autoimmune hemolytic anemia and cold agglutinin disease.

New Insights in Autoimmune Hemolytic Anemia: From Pathogenesis to Therapy Stage 1

Autoimmune hemolytic anemia (AIHA) is a highly heterogeneous disease due to increased destruction of autologous erythrocytes by autoantibodies with or without complement involvement. Other pathogenic mechanisms include hyper-activation of cellular immune effectors, cytokine dysregulation, and ineffective marrow compensation. AIHAs may be primary or associated with lymphoproliferative and autoimmune diseases, infections, immunodeficiencies, solid tumors, transplants, and drugs. The direct antiglobulin test is the cornerstone of diagnosis, allowing the distinction into warm forms (wAIHA), cold agglutinin disease (CAD), and other more rare forms. The immunologic mechanisms responsible for erythrocyte destruction in the various AIHAs are different and therefore therapy is quite dissimilar. In wAIHA, steroids represent first line therapy, followed by rituximab and splenectomy. Conventional immunosuppressive drugs (azathioprine, cyclophosphamide, cyclosporine) are now considered the third line. In CAD, steroids are useful only at high/unacceptable doses and splenectomy is uneffective. Rituximab is advised in first line therapy, followed by rituximab plus bendamustine and bortezomib. Several new drugs are under development including B-cell directed therapies (ibrutinib, venetoclax, parsaclisib) and inhibitors of complement (sutimlimab, pegcetacoplan), spleen tyrosine kinases (fostamatinib), or neonatal Fc receptor. Here, a comprehensive review of the main clinical characteristics, diagnosis, and pathogenic mechanisms of AIHA are provided, along with classic and new therapeutic approaches.