Warm autoimmune hemolytic anemia is an IgM–IgG immune complex disease

Lymphocyte alterations in patients with Common Variable Immunodeficiency (CVID) and autoimmune manifestations

INTRODUCTION

Autoimmunity is a common feature in CVID patients. To date the mechanisms leading to the development of such complications are not fully elucidated.

MATERIALS AND METHODS

Data from 122 CVID patients subdivided in three groups based on the absence of autoimmunity (n-AI) or the presence of hematologic autoimmune phenomena (Cy-AI) or non-hematologic autoimmune phenomena (n-Cy-AI) were evaluated.

RESULTS

We identified a total of 128 autoimmune manifestations in 55/122 patients (45.1%). 30/122 (24.6%) patients presented hematologic autoimmune phenomena while 29/122 (23.8%) presented gastrointestinal autoimmune involvement. Immune thrombocytopenia was the most common manifestation (27/122; 22.1%), followed by autoimmune hemolytic anemia (18/122; 14.8%) and autoimmune enteropathy (17/122; 13.9%). Cy-AI patients displayed higher CD4⁺ effector memory and terminally differentiated CD8⁺ cells with lower percentages of naïve and recent thymic emigrants (RTEs) CD4⁺ cells and a significant expansion of the CD19^hiCD21^low population.

CONCLUSIONS

CVID patients developing autoimmune cytopenias display characteristic immune phenotypic features.

"Ways in which the neonatal Fc-receptor is involved in autoimmunity"

Since the neonatal IgG Fc receptor (FcRn) was discovered, its role has evolved from immunoglobulin recycling and biodistribution to antigen presentation and immune complex routing, bringing it to the center of both humoral and cellular immune responses. FcRn is thus involved in the pathophysiology of immune-related diseases such as cancer, infection, and autoimmune disorders. This review focuses on the role of FcRn in autoimmunity, based on the available data from both animal models and human studies. The knowledge concerning ways in which FcRn is involved in autoimmune response has led to the development of inhibitors for the treatment of autoimmune diseases, also described here. Up to date, the literature remains scarce, shedding light on the need for further studies to fully understand the various pathophysiological roles of this unique receptor.

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FcRn is an intracellular receptor with a key role in IgG and immune complex management.

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FcRn-targeting therapies are a promising way of treatment in antibodies mediated diseases.

Establishment and evaluation of a general dissociation technique for antibodies in circulating immune complexes

This study aimed to establish a general and efficient dissociation technique for detecting antibodies in circulating immune complexes (CICs) in serum and to evaluate its clinical application. CICs were efficiently separated from specimens using polyethylene glycol double-precipitation. The best conditions for anti-HBs dissociation from HBsAg-ICs were a pH of 1.80, incubation at 15 °C for 5–10 min, and detection within 10 min after neutralization. The mean dissociation rate, reproducibility, mean dissociation recovery rate and specificity of the new technique were 64.3%, < 5.97, 95.4 and 100%, respectively. They had a favourable linear relationship (r = 0.9932), and the stability of the reagents exceeded 24 months, except the CIC antibody dissociation reagent (> 12 months). Conditions for the dissociation of other CICs tested were similar, but there were differences in the rate of antibody dissociation. Different HBV-M patterns had significantly different levels and rates of antibody dissociation from HBsAg-IC (P < 0.05), and the detection rates of the corresponding antibodies in HCV, core-anti-HCV core antibody (HCV-ICs), HIV P24-anti-HIV P24 antibody (HIV-ICs), insulin-anti-insulin antibody (INS-ICs) and thyroid globulin-anti-thyroid globulin antibody CICs (TG-ICs) were 34.8, 66.7, 20 and 14.3%, respectively. These data suggest that our CIC antibody dissociation technique is a good general pretreatment technique for the detection of antibodies after the precipitation, separation and dissociation of multiple CICs.

A novel general and efficient technique for dissociating antigen in circulating immune complexes

Circulating immune complexes (CICs) are produced during the immune response. It is more clinically important to establish a general and efficient CICs dissociation technique for the detection of antigens for CICs other than the detection of free antigens in the serum. Polyethylene glycol (PEG) two-precipitation separation and glycine-HCl as a buffer system were employed to develop a general and efficient buffer dissociation technique to separate CICs from serum and dissociate antigens from CICs. The measurement value of new PEG two-precipitation separation technique was higher than traditional PEG precipitation separation technique. There were slight differences in the dissociation conditions of HCV Core-IC, HIV P24-IC, Ins-IC and TG-IC as compared to HBsAg-IC. The detection of antigens in HBsAg-IC, HCV Core-IC, HIV P24-IC, Ins-IC and TG-IC with this technique was superior to that with HCl Dissociation, Trypsin Digestion or Immune Complex Transfer technique. PEG two-precipitation dissociation technique may reduce macromolecular protein and the adhesion of free antigens during the co-precipitation, which increases the efficiency of separation and precipitation of CICs. This technique also avoids the damage of reagents to antigens, assuring the repeatability, reliability and validity. Thus, this technique is application in samples negative or positive for free antigens.

Warm Autoimmune Hemolytic Anemia: Clinical Profile and Management

Background

Autoimmune hemolytic anemia (AIHA) is a rare autoimmune disease in which autoantibodies target red blood cells leading to marked decrease in their lifespan. The classification of AIHA is based on the immunochemical properties of the RBC autoantibody. Warm antibody AIHA (wAIHA) accounts for 75-80% of all adult AIHA cases. The treatment of wAIHA is mainly corticosteroids. Our retrospective study aimed to study the clinical profile and management of wAIHA.

Methods

Data of 75 patients admitted with wAIHA or presented to outpatient department (previous medical records) with wAIHA between January 2003 and January 2016 were analyzed.

Results

In our study, females constituted 12 and 26 patients of primary and secondary wAIHA, while males constituted 17 and 20 patients of primary and secondary wAIHA, respectively. Mean hemoglobin level at AIHA onset was found to be 7.1 ± 1.7 g/dL in primary wAIHA group and 6.3 ± 1.2 g/dL in secondary wAIHA group, which is statistically significant. Splenectomy was used as mode of treatment in one (3.4%) patient of primary wAIHA group and 15 (32.60%) patients of secondary wAIHA group, which is statistically significant. Mean age of wAIHA onset was 69.7 ± 21.5 years in wAIHA group secondary to lymphoma and 54.3 ± 25.7 years in other wAIHA group, which is statistically significant.

Conclusion

The most common causes of secondary wAIHA are B-cell lymphoma, systemic lupus erythematosus, rheumatoid arthritis, chronic lymphocytic leukemia (CLL), common variable immune deficiency, renal cell carcinoma and secondary to drug usage (alpha methyldopa and carbamazepine), respectively. Reducing the cumulative dose of corticosteroids with second line treatment whenever possible and therefore reducing the risk of sepsis, specifically in older patients with comorbidities will reduce morbidity and mortality.

Warm Autoimmune Hemolytic Anemia and Direct Antiglobulin Testing With a False-Negative Result in a 53-Year-Old Man: The DAT Will Set You Free

Warm autoimmune hemolytic anemia (WAIHA), the most common of the relatively uncommon autoimmune-mediated hemolytic anemias (AIHAs), is mediated by polyclonal immunoglobulin (Ig)G autoantibodies in most cases. Herein, we present a case of WAIHA involving a direct antiglobulin test (DAT) with an initially negative result. Using a modified DAT protocol, repeat testing of the same specimen material from a previously healthy 53-year-old man yielded positive results. This case demonstrates that investigation of an apparently negative DAT result plays a critical role in the differential diagnosis of patients with rapidly progressing hemolytic anemia and the reversal of that decline.

Autoimmune haemolytic anaemia: a review and report of four cases

Treatment of autoimmune haemolytic anaemia is still a challenge to clinicians. Even today it may be lethal. Half of the cases are secondary due to an underlying disease, and the others are primary or idiopathic cases. According to the specificity and type of autoantibodies there are warm and cold type forms of autoimmune haemolytic anaemia. The hallmark of the diagnosis is to detect the presence of haemolysis by clinical and laboratory signs and detect the underlying autoantibodies. Treatment of autoimmune haemolytic anaemia is still a challenge to clinicians. We still loose patients due to excessive haemolysis or severe infections caused by immunosuppression. First line treatment is corticosteroids. Other immunosuppressive agents like: cyclophosphamide, azathioprine, cyclosporine or the off label rituximab can be used in case of corticosteroid refractoriness. Splenectomy is a considerable option in selective cases. The authors discuss treatment options and highlight difficulties by presenting 4 cases. Orv. Hetil., 2015, 156(11), 449–456.

Immunotherapy treatments of warm autoimmune hemolytic anemia

Warm autoimmune hemolytic anemia (WAIHA) is one of four clinical types of autoimmune hemolytic anemia (AIHA), with the characteristics of autoantibodies maximally active at body temperature. It produces a variable anemia—sometimes mild and sometimes severe. With respect to the absence or presence of an underlying condition, WAIHA is either idiopathic (primary) or secondary, which determines the treatment strategies in practice. Conventional treatments include immune suppression with corticosteroids and, in some cases, splenectomy. In recent years, the number of clinical studies with monoclonal antibodies and immunosuppressants in the treatment of WAIHA increased as the knowledge of autoimmunity mechanisms extended. This thread of developing new tools of treating WAIHA is well exemplified with the success in using anti-CD20 monoclonal antibody, Rituximab. Following this success, other treatment methods based on the immune mechanisms of WAIHA have emerged. We reviewed these newly developed immunotherapy treatments here in order to provide the clinicians with more options in selecting the best therapy for patients with WAIHA, hoping to stimulate researchers to find more novel immunotherapy strategies.

The enigmatic autoimmune response in endemic pemphigus foliaceus

Endemic pemphigus foliaceus, known as Fogo Selvagem (FS) in Brazil, is a disease characterized by subcorneal blisters and IgG4 anti-dermoglein 1 (Dsg1) autoantibodies. Epidemiological studies of FS strongly an environmental etiology. A 15-year surveillance of the Limao Verde Amerindian reservation in Brazil has uncovered information on the transition of the autoimmune response from the pre-clinical stage to disease state. This incubation time may evolve over several years. The serological markers of the pre-clinical state of FS are IgM anti-Dsg1, IgE and non-IgG4 autoantibodies against Dsg1. The disease stage of FS is characterized by the rise of pathogenic IgG4 anti-Dsg1 autoantibodies. In this review, the authors reviewed the literature on the relevance of the humoral autoimmune response of FS as well as the possible environmental triggers of anti-Dsg1 autoantibody formation. Based on epidemiological observations, the authors hypothesize that the pathogenic IgG4 response in FS may be triggered by hematophagous insect bites.

Advances in pemphigus and its endemic pemphigus foliaceus (Fogo Selvagem) phenotype: a paradigm of human autoimmunity

Pemphigus encompasses a group of organ specific, antibody mediated autoimmune diseases of the skin characterized by keratinocyte detachment that leads to the development of blisters and erosions, which can become life-threatening. The pathogenic autoantibodies recognize desmogleins, which are members of the desmosomal cadherin family of cell adhesion molecules. Desmoglein 3 is targeted in pemphigus vulgaris while desmoglein 1 is targeted in pemphigus foliaceus and its endemic form, Fogo Selvagem. This review will briefly define the salient features of pemphigus and the proposed steps in pathogenesis. We will then summarize the most recent advances in three important areas of investigation: (i) epidemiologic, genetic, and immunologic features of Fogo Selvagem, (ii) molecular mechanisms of injury to the epidermis, and (iii) novel therapeutic strategies targeting specific steps in disease pathogenesis. The advances in each of these three seemingly separate areas contribute to the overall understanding of the pemphigus disease model. These recent advancements also underscore the dynamic interplay between the treatment of patients in a clinical setting and basic science research and have led to an integrative understanding of disease pathogenesis and treatment, allowing pemphigus to serve as a paradigm of human autoimmunity.

The IgM anti-desmoglein 1 response distinguishes Brazilian pemphigus foliaceus (fogo selvagem) from other forms of pemphigus

Fogo selvagem (FS) and pemphigus foliaceus (PF) possess pathogenic IgG anti-desmoglein 1-(Dsg1) autoantibodies. Although PF occurs sporadically, FS is endemic in Limao Verde (LV), Brazil (3.4% prevalence). IgM anti-Dsg1 were detected in 58% FS LV patients (n=31), 19% of FS patients from Hospital-Campo Grande (n=57), 19% from Hospital-Goiania (n=42), 12% from Hospital-Sao Paulo (n=56), 10% of PF patients from United States (n=20), and 0% of PF patients from Japan (n=20). Pemphigus vulgaris (n=40, USA and Japan), bullous pemphigoid (n=40, USA), and healthy donors (n=55, USA) showed negligible percentages of positive sera. High percentages of positive IgM anti-Dsg1 were found in healthy donors from four rural Amerindian populations (42% of 243) as compared with urban donors (14% of 81; P<0.001). More than 50% of healthy donors from LV (n=99, age 5-20 years) possess IgM anti-Dsg1 across ages, whereas IgG-anti-Dsg1 was detected in 2.9% (age 5-10 years), 7.3% (age 11-15 years), and 29% of donors above age 16. IgM anti-Dsg1 epitopes are Ca2+ and carbohydrate-independent. We propose that IgM anti-Dsg1 are common in FS patients in their native environment and uncommon in other pemphigus phenotypes and in FS patients who migrate to urban hospitals. Recurrent environmental antigenic exposure may lead to IgM and IgG responses that trigger FS. JID JOURNAL CLUB ARTICLE: For questions, answers, and open discussion about this article please go to http://network.nature.com/group/jidclub.

[Antibody-mediated cell-specific hematopoietic autoimmune disorders]

Although it is clear that immunologic mechanisms play a significant role in the pathophysiology of many hematologic diseases, there are relative few situations where it is possible to gain a detailed understanding of immune damage in vivo in humans. Autoimmune hemolytic anemia, immune thrombocytopenia and immune neutropenia as antibody-mediated cell-specific disorders are of particular interest in this regard. Autoimmune hemolytic anemia represents a group of disorders in which individuals produce antibodies directed toward one or more of their own erythrocyte membrane antigens. This leads to destruction of the antibody-coated erythrocytes. The pathophysiology of the decreased erythrocyte survival has been examined with increasing sophistication for many years. This paper first discusses the underlying mechanisms responsible for autoimmune hemolytic anemias then consider immune thrombocytopenia and immune neutropenia.

Markedly Increased Vitamin B12 Concentrations Attributable to IgG–IgM–Vitamin B12 Immune Complexes

Background: High serum vitamin B12 concentrations have been reported in patients with hepatic disease, disseminated neoplasia, myeloproliferative disorders, and hypereosinophilic syndromes. We recently discovered an extraordinarily increased vitamin B12 concentration in a patient without these underlying conditions.

Methods: Affinity and size-exclusion chromatography, sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and ELISA methods were used to determine the cause of the increased vitamin B12 concentrations in this patient’s serum.

Results: The protein G column eluates from 2 apparently healthy volunteers and 2 patients with recent vitamin B12 treatment for anemia had vitamin B12 concentrations of &lt;74 pmol/L, whereas the vitamin B12 concentration in the protein G column eluate from the patient was 7380 pmol/L. The elution profile from size-exclusion chromatography of vitamin B12-binding proteins in the patient’s serum revealed an abnormal vitamin-B12-binding protein. SDS–PAGE analysis of the concentrated eluates from the protein G column, under reducing conditions, revealed an additional band with an apparent molecular mass of 76 kDa, which was not present in control column eluates. MALDI-TOF MS identified this band as an IgM heavy chain. By use of a modified ELISA, we determined that the IgM present in the patient’s eluates was associated with the IgG to form IgG-IgM immune complexes.

Conclusions: This case demonstrates the unusual circumstance of a patient with markedly increased vitamin B12 concentrations attributed to immune complexes composed of IgG, IgM, and vitamin B12 and illustrates techniques that can be used to identify this occurrence.

IgG2 containing IgM-IgG immune complexes predominate in normal human plasma, but not in plasma of patients with warm autoimmune haemolytic anaemia

The different physicochemical and sterical properties of IgG subclasses may favour a selective enrichment of defined IgG subclasses in IgM-IgG immune complexes (IC) of human plasma under physiological conditions. Such enrichment of IgG subclasses in IgM-IgG IC of plasma may differ from the normal IgG subclass distribution in plasma itself, and contribute to the physiological functions of IgM-IgG IC. Systematic studies on the IgG subclass distribution in IgM-IgG IC in humans are lacking. Using specific analytical techniques to characterise IgM-IgG IC in human plasma (i.e. fast protein liquid chromatography, enzyme-linked immunosorbent assay, affinity biosensor technology), and taking warm autoimmune haemolytic anaemia (WAIHA) of humans as a disease model, we here demonstrate that: (i) IgG2 is the predominant IgG subclass in IgM-IgG IC under physiological conditions, (ii) the predominance of IgG2 within IgM-IgG IC may get lost in polyclonal IgG-mediated autoimmune disease and (iii) the IgG subclass distribution in IgM-IgG IC influences the interaction between IC and blood cells involved in antigen presentation. The data presented here therefore extend the physiological function of IgG2, which is the protective immune response towards carbohydrate antigens in bacterial infections, and suggest IgG2-dependent regulation of immune responses to self-immunoglobulin in humans. The disturbed IgG subclass distribution in IgM-IgG IC of patients with WAIHA might influence activity of self-reactive B cells involved in the pathophysiology of the disease.

Survey of the year 2005 commercial optical biosensor literature

We identified 1113 articles (103 reviews, 1010 primary research articles) published in 2005 that describe experiments performed using commercially available optical biosensors. While this number of publications is impressive, we find that the quality of the biosensor work in these articles is often pretty poor. It is a little disappointing that there appears to be only a small set of researchers who know how to properly perform, analyze, and present biosensor data. To help focus the field, we spotlight work published by 10 research groups that exemplify the quality of data one should expect to see from a biosensor experiment. Also, in an effort to raise awareness of the common problems in the biosensor field, we provide side-by-side examples of good and bad data sets from the 2005 literature.