Sublytic Terminal Complement Components Induce Eryptosis in Autoimmune Haemolytic Anaemia Related to IgM Autoantibodies

BACKGROUND/AIMS: Eryptosis, the suicidal death of red blood cells (RBCs), is characterized by phosphatidylserine (PS) exposure at the cell surface. It can be catalysed by a variety of abnormal conditions and diseases. Until now, the many questions surrounding the physiology and pathophysiology of eryptosis have not been sufficiently answered. Recently, we demonstrated IgM and IgA autoantibodies (aab) to induce PS exposure on circulating RBCs of patients with autoimmune haemolytic anaemia (AIHA). However, it remained unclear how these aab lead to eryptosis. METHODS: Serum and plasma samples from patients with clinically relevant AIHA of cold type were used to induce eryptosis in O RBCs. Serum containing fresh complement from healthy donors, antibodies to complement component, and complement factor depleted sera were added to examine the influence of the complement on PS-exposure. RBC bound annexin V PE were analysed by flow cytometry. RESULTS: Eryptosis related to IgM aab was found to be dependent on complement activation and could be effectively inhibited by EDTA, serum heat inactivation and anti-C5. PS exposure increased with sequential activation of the sublytic terminal complement components C5b6, C5b-7 and was most significant at the C5b-8 stage. A decrease was observed following the formation of the lytic membrane attack complex C5b-9, either because of lysis of eryptotic RBCs or because of inhibition of eryptosis by C9. CONCLUSION: Our findings reflect new aspects on RBC destruction in AIHA as well the impact of the terminal complement complexes on the RBC membrane. The striking differences to nucleated cell apoptosis may even have physiological meaning of RBC acting as a buffer of the complement system

Oxidative Stress Is Predominant in Female but Not in Male Patients with Autoimmune Thrombocytopenia

As the involvement of oxidative stress (OS) in autoimmune thrombocytopenia (AITP) has been reported, a fast and rapid test for the reliable measurement of OS and antioxidant capacities (AOCs) might be a useful tool in extending current diagnostic possibilities. The free oxygen radical test (FORT) and free oxygen radical defence (FORD) assay (Callegari, Italy) are easy to perform and reliable, with results available within 15 minutes. Thirty-seven AITP patients and 37 matched healthy individuals were included in this study. All participants responded to a standard questionnaire provided by these assays. Female patients with AITP were observed to demonstrate significantly higher OS in comparison to female controls (P=0.0027) and male AITP patients (P=0.0018). The AOCs were not reduced in patients with AITP (P=0.7648). Correlation of OS with platelet count identified a weak positive correlation (P=0.0327, Spearman R=0.4672). The questionnaire revealed that ITP patients in comparison to healthy controls are more stressed, feel exhausted and fatigued, and eat a healthier diet. In conclusion, OS is predominant in female but not in male patients with AITP suggesting gender-specific differences in the pathomechanisms of AITP. Identification of patients with high levels of OS might be beneficial in the management of AITP

‘Chameleonic' Serological Findings Leading to Life-Threatening Hemolytic Transfusion Reactions

Background: The phenomena of co-incidence of transfusion-induced allo- and autoantibodies, blockage and/or loss of red blood cell (RBC) antigens are conspicuous and may result in confusion and misdiagnosis. Case Report: A 67-year-old female was transferred to the intensive care unit due to hemolysis which developed 2 days following transfusion of three Rh(D)-negative RBC units in the presence of strongly reactive autoantibodies. Standard serological testing and genotyping were performed. Upon arrival, the patient was typed as Ccddee. Her hemolysis was decompensated, and an immediate blood transfusion was required. In addition, direct and indirect antiglobulin tests (DAT and IAT) as well as the eluate were strongly positive. Emergency transfusion of Rh(D)-negative RBCs resulted in increased hemolysis and renal failure. An exhaustive testing revealed anti-D, anti-c, CCddee phenotype and CCD.ee genotype. Three units of cryopreserved CCddee RBCs were transfused, and the patient's condition immediately improved. The discrepancy between Rh-D phenotyping and genotyping was likely caused by masking of the D-epitopes by the autoantibodies. In fact, further enquiry revealed that the patient had been phenotyped as Rh(D)-positive 6 months ago and had been transfused at that time following hip surgery. Conclusion: The phenomena of transfusion-induced autoantibodies, masked alloantibodies, antigen blockage and/or loss are rare but important features which should be considered in patients presenting with autoimmune hemolytic anemia and/or hemolytic transfusion reactions

A fluorometric erythrophagocytosis assay using differentiated monocytic THP‐1 cells to assess the clinical significance of antibodies to red blood cells

Background and objectives: The significance of antibodies to red blood cells (RBCs) is variable and cannot be predicted solely by serological testing. A flow cytometry-based erythrophagocytosis assay was established using phorbol 12-myristate 13-acetate (PMA)-treated THP-1 cells and RBCs labelled with PKH26 to assess allo- and autoantibodies to RBCs. Materials and methods: THP-1 cells were differentiated into macrophage-like cells by treatment with PMA. RBC samples coated with alloantibodies or autoantibodies were obtained from 16 patients with autoimmune haemolytic anaemia of warm type (wAIHA) as well as from five pregnant women with warm autoantibodies. RBCs from healthy blood donors were used as controls. RBCs were labelled with the red lipophilic fluorescent dye PKH26 and incubated with PMA-treated THP-1 cells. After removal of nonadherent RBCs by washing and haemolysis of adherent RBCs, erythrophagocytosis was quantified by flow cytometry. Results: We observed significant phagocytosis of RBCs coated with clinically relevant alloantibodies (i.e. anti-D and anti-K) or autoantibodies from patients with active wAIHA, but not of those coated with alloantibodies (anti-Ch) or autoantibodies from patients and pregnant women without haemolysis. Conclusion: The flow cytometry-based erythrophagocytosis test described here is quantitative, highly reliable, and may be helpful for the assessment of the clinical significance of antibodies to RBCs

Treatment of 5 dogs with immune-mediated thrombocytopenia using Romiplostim

Background Immune thrombocytopenia (ITP) in dogs is analogous to that in humans. Romiplostim, a novel thrombopoietin receptor (TPO-R) agonist, is currently used for the treatment of refractory ITP in humans, but not in dogs. Here, we describe the response to romiplostim in five dogs with refractory ITP. Five dogs with severe and refractory ITP (three primary and two secondary) received romiplostim subcutaneously. Four dogs were administered 3–5 μg/kg and one dog received 10–13 μg/kg body weight once weekly. Results Romiplostim was well-tolerated and administration was associated with an increase in platelet counts in all five dogs. Four of the five dogs entered remission and relapses were not observed over a follow-up period of 3–10 months. Conclusions Romiplostim is effective in the treatment of ITP in dogs at least as well as in humans. This finding may help to develop and use new therapeutics for ITP in dogs and humans

Hematopoietic progenitor cells and interleukin-stimulated endothelium: expansion and differentiation of myeloid precursors

<p>Abstract</p> <p>Background</p> <p>Cytokine-stimulated endothelial cells (EC) propagate hematopoietic progenitor cell (HPC) expansion. However, the effects on the functional capacities of cultured progenitors have not been evaluated. HPC were assessed by flow cytometry, colony and cobblestone assays and long-term cultures (LTC) after culturing in the supernatant of EC stimulated by IL-1β, IL-3 or IL-6.</p> <p>Results</p> <p>EC incubation with IL-6 did not improve cell expansion in comparison to non-stimulated EC supernatant, while the HPCs' phenotype and functional capacities were retained. In contrast, IL-1β and IL-3 stimulation resulted in a 10- and 100-fold increase in cell numbers with more than 90% of these cells being CD33(+). Plating efficiencies and LTC initiating cells were greatest in IL-6 supernatants, whereas the highest numbers of burst-forming units were observed using IL-3. IL-1β supernatants diminished the number of 5-week cobblestone-areas, whereas the number of 2-week cobblestone areas remained equal to freshly isolated HPC. Fewer 2-week cobblestones and greater amounts of 5-week cobblestones were observed with IL-6 and IL-3. Expanded progenitors from all interleukin conditions were further matured into functional granulocytes.</p> <p>Conclusion</p> <p>IL-1β and IL-3 stimulated endothelium induces proliferation and differentiation of myeloid precursors, while IL-6 treatment induced a benefit of HPC survival.</p

Risk of piperacillin‐induced hemolytic anemia in patients with cystic fibrosis and antipseudomonal treatment: a prospective observational study

BACKGROUND: Drug-induced immune hemolytic anemia (DIIHA) is a rare but severe side effect caused by numerous drugs. Case reports and case series suggest that piperacillin-related DIIHA may be more common among patients with cystic fibrosis (CF). However, the prevalence is speculative. The aim of this prospective, observational study was determine the prevalence of DIIHA in such affected patients. METHODS AND MATERIALS: Patients with CF hospitalized for parenteral antibiotic therapy at Charité Universitätsmedizin Berlin, who had previously been exposed to IV antibiotics, were enrolled. Blood samples were collected on Days 3 and 12 of antibiotic treatment courses. Serological studies were performed using standard techniques with gel cards. Screening for drug-dependent antibodies (ddab) was performed in the presence of the drugs and their urinary metabolites. RESULTS A total of 52 parenteral antibiotic cycles in 43 patients were investigated. Ddab against piperacillin were detected in two patients (4.7%). The direct AHG was positive with anti-IgG only in both patients. However only one of these patients developed mild immune hemolytic anemia. Both patients had been repeatedly treated with piperacillin without any evident hemolysis. There was no correlation between the exposure to piperacillin and the prevalence of ddab. CONCLUSION: Our prospective study indicates that piperacillin-induced ddab occur more frequently in patients with CF than previously suggested. The question related to the significance of piperacillin-dependent antibodies may reflect new aspects in this field

Advances in ITP – Therapy and Quality of Life – A Patient Survey

Current guidelines recommend glucocorticoids and splenectomy as standard 1(st) and 2(nd) line treatments for chronic immune thrombocytopenia (ITP). We sought to find out how German ITP-patients are treated with respect to these guidelines. Members of a patient support association ≥18 years with a self-reported history of chronic ITP>12 months were surveyed with a web-based questionnaire. 122 questionnaires were evaluated. 70% of patients had chronic ITP for more than 5 years and 20% an average platelet count of ≤30·10(9)/L. 41% of the patients reported haematomas or petechiae more than once or twice and up to 12 times or more per year and 17% oropharyngeal and nasal bleeds. 11% had been admitted to hospital during the last 12 months. 88% had received or currently receive glucocorticoids, 27% were splenectomised. IVIG had been given to 55%, rituximab to 22%, anti-D to 12%, ciclosporin to 7%, while complementary and alternative medical treatments had been used by 36%. 50 women responded to questions concerning pregnancy. 14 (28%) had been advised not to become pregnant. 23 reported pregnancies and 10 (44%) required treatment for their ITP during pregnancy. Glucocorticoids are the most common therapy for chronic ITP but complementary and alternative treatments already come second and less than ⅓ of patients are splenectomised. This and the frequent use of complementary medicines suggests patients' dissatisfaction with conventional approaches. Many patients receive off-label therapies. There is a major need for adequate counselling and care for pregnant ITP-patients

Detailed analysis of the variability of peptidylarginine deiminase type 4 in German patients with rheumatoid arthritis: a case control study

Peptidylarginine deiminase type 4 (PADI4) genotypes were shown to influence susceptibility to rheumatoid arthritis ( RA) in the Japanese population. Such an association could not previously be confirmed in different European populations. In the present study, we analysed exons 2 - 4 of PADI4 in 102 German RA patients and 102 healthy individuals to study the influence of PADI4 variability on RA susceptibility by means of haplotype-specific DNA sequencing. Analyses of the influence of PADI4 and HLA-DRB1 genotypes on disease activity and on levels of anti-cyclic citrullinated peptide antibodies were performed. Comparing the frequencies of PADI4 haplotype 4 (padi4\_89* G, padi4\_90* T, padi4\_92* G, padi4\_94* T, padi4\_104* C, padi4\_95* G, padi4\_96* T) ( patients, 14.7%; controls, 7.8%; odds ratio = 2.0, 95% confidence interval = 1.1 - 3.8) and carriers of this haplotype ( patients, 27.5%; controls, 13.7%; odds ratio = 2.4, 95% confidence interval = 1.2 - 4.8), a significant positive association of PADI4 haplotype 4 with RA could be demonstrated. Other PADI4 haplotypes did not differ significantly between patients and controls. Regarding the individual PADI4 variants, padi4\_89 ( A. G), padi4\_90 (C --> T), and padi4\_94 (C --> T) were significantly associated with RA ( patients, 49.5%; controls, 38.7%; odds ratio = 1.6, 95% confidence interval = 1.1 - 2.3). Considering novel PADI4 variants located in or near to exons 2, 3, and 4, no quantitative or qualitative differences between RA patients (8.8%) and healthy controls (10.8%) could be demonstrated. While the PADI4 genotype did not influence disease activity and the anticyclic citrullinated peptide antibody level, the presence of the HLA-DRB1 shared epitope was significantly associated with higher anti-cyclic citrullinated peptide antibody levels ( P = 0.033). The results of this small case - control study support the hypothesis that variability of the PADI4 gene may influence susceptibility to RA in the German population. Quantitative or qualitative differences in previously undefined PADI4 variants between patients and controls could not be demonstrated