Chronic Pure Red Cell Aplasia Research Articles

Pure Red Cell Aplasia Secondary to Parvovirus B19 Infection as a Rare Cause of Anemia in a Dialysis Patient: A Case Report.

Parvovirus B19 infection can cause chronic pure red cell aplasia in immunosuppressed hosts or acute and transient aplastic crises in immunocompetent hosts. In dialysis patients, only transient aplastic crisis induced by parvovirus B19 infection has been reported. We herein report the first case of an adult dialysis patient who developed chronic pure red cell aplasia associated with parvovirus B19 infection. Repeated pneumonia and heart failure may contribute to an immunocompromised status, making the patient more vulnerable to parvovirus B19 infection. This case expands on the differential diagnosis of chronic anemia in patients undergoing dialysis.

Treating Parvovirus Triggered Refractory Hemolytic Anemia with Rituximab in Renal Transplant Recipients - A Report of Two Cases.

Parvovirus B19 is a small (26 nm), nonenveloped, single-stranded DNA (5.6-kb) virus. The only known host for parvovirus B19 is humans. Parvovirus B19 is directly cytotoxic to erythroid precursor cells of the colony- and burst-forming units. Human parvovirus B19 is the etiologic agent of erythema infectiosum and chronic pure red cell aplasia in immunocompromised individuals. Acute parvovirus B19 infection should be suspected in immunocompromised patients, who present with reticulocytopenic hemolytic anemia and thrombocytopenia. Intravenous immunoglobulin (IVIg) is the standard treatment for parvovirus-induced cytopenias. We report two cases of postrenal transplant who presented with reticulocytopenic anemia and were found to have parvovirus infection. They did not respond to conventional treatment with intravenous gamma globulin. Both patients were treated with rituximab with which they had improvement in clinical and hematological parameters. There was no previous documentation of using rituximab in the treatment of parvovirus-triggered autoimmune hemolytic anemia postrenal transplant patients. This article illustrates how rituximab will be helpful in this setting, of course, it is a new thought but requires further studies and validation.

Germline Loss-of-Function Mutations in MDM4 Cause p53-Dependent Hematopoietic Cell Death in Patients with Variable Bone Marrow Failure Phenotypes

The mouse double minute 4 (MDM4) negatively regulates p53 through the p53/MDM2/MDM4 regulatory network and is commonly overexpressed in several cancers. Here, we describe two unrelated pedigrees with germline MDM4 mutations with clinical features of bone marrow (BM) failure. Patient 1 (P1) presented at the age of 11 months with chronic pure red cell aplasia requiring chronic red blood cell transfusions and BM findings with absent erythroid precursors and dysplastic megakaryocytes. Patient 2 (P2) presented at age of 4 weeks with neutropenia with hypogranulation of neutrophils and a normocellular bone marrow with hypoplastic myelopoiesis and dysplasia of all three lineages. Both patients had normal chromosomal breakage and normal for age telomere length in peripheral blood. Whole genome and panel sequencing identified germline heterozygous variants in MDM4: p.Leu31Thrfs*15 in P1 and p.T454M in P2 as the only relevant candidate variants. Both mutations are absent in >140 thousand individuals in gnomAD database, and the constraint analysis indicates that MDM4 gene is intolerant to missense variation (observed to expected (O/E) ratio of 181/258, Z-score 1.71) and highly intolerant to protein truncating variation (O/E: 0/27 with a pLI score of 1). MDM4 protein consists of four key domains: p53 binding N-terminus, an acidic region, a zinc finger domain, and a C-terminal RING domain, which heterodimerizes with MDM2 to ubiquitinate and promote p53 degradation. MDM4 p.T454M missense mutation found in P2 was previously reported by Toufektchan et al. in 2020 in one patient with BM failure phenotype with short telomeres who carried additional TERT variant. The MDM4 p.T454M mutation was shown to result in lower protein levels (consistent with a loss-of-function effect) and had altered capacity to dimerize with the MDM2 RING domain, causing p53 hyperactivity. MDM4 p.Leu31Thrfs*15 mutation described in P1 is localized in the N-terminal p53 binding domain and results in RNA transcript loss, as confirmed by us in patient cells using RNA sequencing showing a two-fold reduction of the dominant transcript [ENST00000367182.8]. This was corroborated by Western blot demonstrating decreased levels of MDM4 protein. We sought to elucidate the impact of p.Leu31Thrfs*15 and p.T454M mutations on hematopoiesis and regulation of p53 expression. In two human induced pluripotent stem cell (iPSC) lines derived from male and female healthy donors, we knocked-in the MDM4 p.T454M and p.Leu31Thrfs*15 mutations by CRISPR/Cas9 engineering. Of note, MDM4 p.Leu31Thrfs*15 homozygous knock-in line could not be established despite multiple attempts. We discovered statistically significant decreased erythroid and myeloid differentiation capacity from MDM4-mutant iPSCs compared to isogenic control iPSCs (p <0.05). There were statistically significantly more AnnexinV+/DAPI+ mutant iPSC-derived myeloid and erythroid progenitors compared to isogenic control-derived progenitors (p <0.05), pointing to a higher rate of cell death in MDM4-mutant cells. We further demonstrated increased expression of p53 and p21 proteins in MDM4 p.Leu31Thrfs*15 iPSC clones. To better understand the loss-of-function effect of MDM4, we knocked out MDM4 in healthy CD34+ cells using CRISPR/Cas9 editing. Knock out of MDM4 with an efficiency of >80% was achieved in multiple biological replicates, resulting in increased p53 activity and fewer blast-forming erythroid (BFU-E) and myeloid colonies compared to control cells that were Cas9-edited at the AAVS1 safe harbor locus. This impairment was rescued by disruption of TP53 gene. Sequencing of individual BFU-E colonies did not reveal any cells with biallelic loss of MDM4, while similar percentages of unedited colonies and heterozygous disrupted MDM4 colonies were detected. Xenotransplantation studies using immunodeficient NBSGW mice are currently underway to explore the impact of MDM4-edited CD34+ cells in vivo. In summary, we describe two patients with germline loss-of-function MDM4 mutations that cause p53 hyperactivity which causes the unifying feature of hematopoietic defect across a BMF disorder spectrum without telomere shortening. Sharma and Bhoopalan are equal contributors

Parvovirus-induced autoimmune hepatitis: First case in the literature

Parvovirus B19 infection is usually self-limiting in immunocompetent individuals. Twenty-five percent of infected individuals are&#x0D; completely asymptomatic during infection, with 50% of them presenting flu-like symptoms and the remaining patients presenting&#x0D; erythema infectiosum, arthralgia, or arthritis. More rarely, transient aplastic crisis is seen in individuals with chronic haemolytic&#x0D; disorders. Chronic pure red cell aplasia and aplastic anaemia may also be observed in immunocompromised patients. There is&#x0D; sufficient evidence in the literature suggesting that B19 infections can also cause a spectrum of liver diseases, ranging from elevated&#x0D; transaminase levels to acute hepatitis, fulminant liver failure, and even chronic hepatitis. This case report discusses a patient with&#x0D; acute parvovirus infection and newly diagnosed autoimmune hepatitis (AIH) and the role of this viral infection in the disease.

T cell clonal expansion and STAT3 mutations: a characteristic feature of acquired chronic T cell-mediated pure red cell aplasia

Acquired chronic pure red cell aplasia (PRCA) develops idiopathically or in association with other medical conditions, including T cell large granular lymphocytic leukemia (T-LGLL) and thymoma. T cell dysregulation is considered a cardinal pathogenesis of PRCA, but genetic-phenotypic associations in T cell abnormalities are largely unclear. We evaluated an extended cohort of 90 patients with acquired PRCA, including 26 with idiopathic, 36 with T-LGLL-associated and 15 with thymoma-associated PRCA, for their T cell immuno-phenotypes, clonalities and STAT3 mutations. TCR repertoire skewing of CD8+ T cells was detected in 37.5% of idiopathic, 66.7% of T-LGLL-associated and 25% of thymoma-associated PRCA patients, and restriction to Vβ1 was most prominent (41%). Clonalities of TCRβ or γ chain and STAT3 mutational status were statistically associated (P = 0.0398), and they were detected in all three subtypes. The overall response rate to cyclosporin A was 73.9%, without significant difference by subtypes nor STAT3 mutational status. The T cell dysregulations, such as TCR repertoire skewing with predominant Vβ1 usage, clonality and STAT3 mutations, were frequently found across the subtypes, and the close associations between them suggest that these T cell derangements reflect a common pathophysiological mechanism among these PRCA subtypes.

Clinical and pathophysiological features of acquired pure red cell aplasia: based on the concept of T-cell dysregulations

Acquired pure red cell aplasia (PRCA) develops in a variety of contexts and thus, should be regarded as a syndrome. The three major subtypes of acquired PRCA are idiopathic PRCA, T cell large granular lymphocytic leukemia (T-LGLL)-associated PRCA, and thymoma-associated PRCA. Although the Japanese National Research Group on Idiopathic Bone Marrow Failure Syndromes of the Ministry of Health, Labor and Welfare of Japan has made significant contributions to our understanding of PRCA, details of its clinical characteristics, and pathophysiological mechanisms remain largely unknown. A recent epidemiological analysis using the JSH Hematologic Disease Registry revealed that approximately 100 new cases with acquired PRCA were diagnosed annually in Japan, which was higher than previously thought to be. The median age of the patients was 73 years. A prospective observational study on chronic PRCA (PRCA2016) is currently ongoing, and it may provide new clinical insights into acquired PRCA. Dysregulation of T cells has been shown to play a central role in PRCA. We studied T cell clonalities and STAT3 mutations in 90 PRCA patients and discovered that clonal T cell expansions were frequently recognized and closely associated with STAT3 mutations in the three major types of PRCA.

Identification of Adverse Risk Factors for Survival in Acquired Pure Red Cell Aplasia Receiving Immunosuppressive Therapy By the Japan PRCA2004/2006 Study and Introduction to the New Cohort Study PRCA2016

Pure red cell aplasia (PRCA) is characterized by normocytic normochromic anemia associated with reticulocytopenia and erythroid hypoplasia in otherwise normal bone marrow. The acquired chronic PRCA may present as a primary hematological disorder in the absence of any other diseases or develop associated with certain conditions such as thymoma, lymphoproliferative disorders, infections, collagen vascular diseases, or after exposure to a wide variety of drugs. Idiopathic PRCA and secondary PRCA not responding to the treatment of the underlying diseases are generally treated by immunosuppressive therapy and the most patients require long-term treatment. Glucocorticoids, cyclosporine and cyclophosphamide are commonly used for initial treatment as monotherapy or combination therapy and majority of the patients respond to immunosuppression. However, most patients treated with these medications relapse during tapering of the treatment. Because of the extreme rarity of this disease, the long-term outcome of chronic PRCA following immunosuppression remains unclear and the adverse risk factors for survival have to be elucidated.In order to identify the adverse risk factors for survival in acquired chronic PRCA following immunosuppression and improve the prognosis, we have conducted nationwide surveys for adult acquired chronic PRCA in Japan. We conducted the first study for adult chronic PRCA in japan in 2004 and 2006 that had been diagnosed between 1990 and 2006 across 109 institutions, and collected the data on a total of 185 patients (PRCA2004/2006 study). We have also started another cohort study in 2016 in collaboration with the Japanese Society of Hematology (JSH) (PRCA2016 study) that was approved by the institutional review board and the ethical committee of the JSH.In PRCA2004/2006 study 73 patients (39%) were classified as having idiopathic PRCA and 112 patients (61%) as having secondary PRCA, including 42 thymoma- and 14 large granular lymphocyte leukemia (LGL)-associated PRCA. The details on idiopathic, thymoma-associated and LGL-leukemia-associated PRCA have been previously reported (Sawada K, et al. Haematologica 2007;92:1021; Hirokawa M, et al. Haematologica 2008;93:27; Fujishima N, et al. Haematologica 2008;93:1555). The last questionnaires for the patients with these three subtypes of PRCA were sent to the institutions in 2012 for collecting the data on relapse, subsequent treatment and efficacy and outcome.The PRCA2004/2006 study revealed that the median overall survival (OS) has not yet been reached in idiopathic PRCA following immunosuppression and the estimated median OS times in thymoma-associated and LGL leukemia-associated PRCA were 142 and 148 months, respectively. Twenty-two deaths were reported and the major causes of death were infection and organ failure (Hirokawa M, et al. Brit J Haematol 2015;169:879). Poor response to induction therapy and relapse of anemia were demonstrated to be associated with death and this was also confirmed by the Mantel-Byar analysis (p<0.001) (Fig. 1). The efficacy of re-induction therapy for relapsing PRCA was inferior to the initial inductive therapy (p<0.001) (Fig. 2).With the results of this study, we have proposed the clinical guidelines for management of PRCA in 2011 and we conducted another cohort study in 2016 in collaboration with the Japanese Society of Hematology (JSH) (PRCA2016 study). The primary endpoint of this study is the OS in chronic PRCA following immunosuppression and the principal aim is to learn whether or not the prognosis would be improved. Between 2006 and 2014, 554 PRCA patients were registered in the JSH hematological disorder registry and we asked the physicians to participate in this study (Fig. 3). The potential size of patient cohort is 181, including 116 idiopathic and 65 secondary PRCA and these patients will be followed up during the next ten years. The PRCA2016 cohort study is expected to reveal the unbiased results regarding the long-term survival and quality of life in PRCA following immunosuppression. [Display omitted] DisclosuresFujisawa:Bristol myers Squibb: Honoraria; Beckman Coulter: Honoraria; Eisai: Honoraria; Janssen Pharmaceutical: Honoraria; Novartis: Honoraria; Astellas: Honoraria, Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Sumitomo Dainippon Pharma: Honoraria; Otsuka Pharmaceutical: Honoraria, Research Funding; SHIONOGI CO, LTD: Honoraria, Research Funding; Shire plc: Honoraria; Alexion Pharmaceutical: Honoraria; Pfizer: Honoraria, Research Funding; Ono Pharmaceutical: Honoraria, Research Funding; Takeda Pharmaceuticals: Honoraria, Research Funding; Celgene: Honoraria; Chugai Pharmaceutical: Honoraria, Research Funding; Kyowa Hakko Kirin: Research Funding; MSD: Research Funding. Yonemura:Alexion Pharma GK: Honoraria, Research Funding. Kurokawa:Pfizer Inc.: Research Funding; Celgene Corporation: Speakers Bureau; Nippon Shinyaku Co., Ltd.: Other: Scholarship donations for the laboratory, Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Takeda Pharmaceutical Company Limited.: Research Funding, Speakers Bureau; Astellas Pharma Inc.: Research Funding.

Clonal hematopoiesis in adult pure red cell aplasia

Idiopathic pure red cell aplasia (PRCA) and secondary PRCA associated with thymoma and large granular lymphocyte leukemia are generally considered to be immune-mediated. The PRCA2004/2006 study showed that poor responses to immunosuppression and anemia relapse were associated with death. PRCA may represent the prodrome to MDS. Thus, clonal hematopoiesis may be responsible for treatment failure. We investigated gene mutations in myeloid neoplasm-associated genes in acquired PRCA. We identified 21 mutations affecting amino acid sequences in 11 of the 38 adult PRCA patients (28.9%) using stringent filtering of the error-prone sequences and SNPs. Four PRCA patients showed 7 driver mutations in TET2, DNMT3A and KDM6A, and 2 PRCA patients carried multiple mutations in TET2. Five PRCA patients had mutations with high VAFs exceeding 0.3. These results suggest that clonal hematopoiesis by stem/progenitor cells might be related to the pathophysiology of chronic PRCA in certain adult patients.

Somatic Mutations of Myeloid Malignancy-Associated Genes in Acquired Pure Red Cell Aplasia in Adults

Background. Idiopathic pure red cell aplasia (PRCA) and secondary PRCA not responding to the treatment of the underlying diseases are generally thought be immune-mediated and treated by immunosuppressive therapy. We previously conducted the PRCA2004/2006 study and reported that poor response to induction therapy and relapse of anemia were associated with death. Principal causes of death were infections and organ failure. Based on the literatures, idiopathic PRCA may represents the prodrome to myelodysplastic syndromes. Theoretically, there are two potential mechanisms of unresponsiveness to immunosuppression; the clonal hematopoiesis by the stem/progenitor cells that have undergone somatic mutations during disease progression of PRCA and the clonal changes of auto-aggressive lymphocytes reacting against erythroid progenitors.Objectives. In this study, we investigated the somatic mutations of myeloid malignancy-associated genes in acquired PRCA in order to determine how often clonal hematopoiesis is detected in this disorder.Materials and Methods. This study included 23 patients with chronic acquired PRCA (12 idiopathic, 7 thymoma-, 2 LGL leukemia- and 2 systemic lupus erythematosus-associated PRCA) with a median age of 62 (range: 40-62). Disease status was varying. After obtaining informed consent, heparinized blood was drawn and mononuclear cells were separated by density gradient centrifugation. Extracted genomic DNA samples were subjected to targeted sequencing for 54 myeloid malignancy-associated genes using a TruSight Myeloid Sequencing Panel kit according to the manufacturer's instruction (Illumina). Criteria for the significant somatic mutations of myeloid malignancy-associated genes in the present study were as follows: potential functional consequences such as missense, nonsense or frameshift mutations; exclusion of previously reported SNPs; being recurrently detected in two sequencing runs; variant allele frequency (VAF) exceeding 0.02 and less than 0.40. The institutional review board approved the experimental protocol.Results. We detected some mutations of the targeted genes in 20 out of 23 patients, and the somatic mutations defined by the criteria mentioned above were found in 10 patients including 6 idiopathic, 3 thymoma-associated and one LGL leukemia-associated PRCA (Fig. 1). These 10 patients had 38 distinct mutations in 20 genes. Variant allele frequencies were 0.02 to 0.37 (median, 0.04; average, 0.06, Fig. 2). Four patients had more than one mutated genes and multiple genes were mutated in some patients (Fig. 1). The most frequently mutated gene was CUX1 that was found in four patients, and STAG2, DNMT3A, KDM6A, SMC3A, ASXL1, TET2 and TP53 were mutated in more than one patient.Discussion/Conclusion. This study demonstrated that myeloid malignancy-associated genes were somatically mutated in 43% of acquired chronic PRCA patients. This figure appears to exceed the prevalence rate of clonal hematopoiesis of indeterminate potential (CHIP) in the general population with the age of 60s. These mutations were presumably carried by monocytes, because DNA samples were prepared from PBMCs in this study cohort. Profiles of mutated genes in PRCA appear to be different from those of aplastic anemia that were previously reported by other groups. It is yet to be known whether this could result from the different nature of both diseases, or the difference in the experimental protocols. Our findings strongly encourage conducting a prospective study to confirm our observation and clarify the diagnostic and predictive values of somatic mutations of myeloid malignancy-associated genes in acquired PRCA. This project is ongoing in collaboration with the prospective cohort study PRCA2016 being conducted in Japan. [Display omitted] DisclosuresNakao:Kyowa Hakko Kirin Co., Ltd.: Honoraria; Novartis: Honoraria; Alexion Pharmaceuticals, Inc.: Consultancy, Honoraria. Matsuda:GlaxoSmithKline K.K.: Honoraria; Novartis Pharma K. K.: Honoraria; Chugai Pharmaceutical Co, Ltd.: Honoraria; Kyowa Hakko Kirin Co, Ltd.: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Nippon Shinyaku Co., Ltd.: Honoraria; Celgene Corporation: Honoraria; Alexion Pharmaceuticals, Inc.: Honoraria; Sanofi K.K.: Honoraria; Beckman Coulter K.K.: Honoraria. Mitani:Kyowa Hakko Kirin Co., Ltd.: Consultancy, Research Funding, Speakers Bureau; Bristol-Myesr Squibb: Research Funding, Speakers Bureau; Celgene: Speakers Bureau; Chugai: Research Funding; Astellas: Research Funding; Sumitomo Dainippon: Research Funding; Novartis: Research Funding; Toyama Chemical: Research Funding.

Adult Patients with Acquired Pure Red Cell Aplasia: Treated By Cyclosporine a and/or Corticosteroids--Single Center Experience

▪Objective: Adult pure red cell aplasia (PRCA) is a syndrome characterized by a severe normocytic anemia, reticulocytopenia, and absence of erythroblasts from an otherwise normal bone marrow. Immunosuppressive therapy has been used as the initial treatment for acquired chronic PRCA. This article aims to evaluate the efficacy of cyclosporine A, and/or corticosteroids, and possible factors influencing it.Methods: 34 cases of PRCA were retrospectively analyzed at our institution.Clinical data of 23 inpatient cases and 11 outpatient cases from 2009 October to 2016 March were collected. These patients were treated by cyclosporine A (CsA), and/or corticosteroids (CS).Results: The causes of PRCA were as follows (table 1): idiopathic (15 cases, 44.1%), thymoma-associated (5 cases, 14.7%), and large granular lymphocyte (LGL) leukaemia-associated (7 cases, 20.6%), virus infection (4 cases, 11.7%), major ABO-mismatched allogeneic haematopoietic stem cell transplantation (1 case, 2.94%), rheumatoid arthritis (1 case, 2.94%), antierythropoietin antibody-mediated (1 case, 2.94%). One patient was lost to follow-up. Two patients were not evaluable for response due to short observation period (<3 months). In idiopathic PCRA, complete remission (CR) was achieved in 4 of 14 cases (28.6%), and partial remission (PR) was achieved in 7 patients (50.0%), while 1 case (7.1%) was still transfusion dependent and 2 deaths(14.3%). In secondary PRCA, complete remission (CR) was achieved in 6 of 17 cases (35.3%, 3 LGL, 2 thymoma, 1 others), and partial remission (PR) was achieved in 3 patients (17.6%, 1 LGL, 2 others ), while 7 case (41.2%, 3 LGL, 2 thymoma, 2 others)) were still transfusion dependent and 1 death(5.9%, thymoma). It showed that the initial rate of CR in CsA-containing group was higher than CS alone (33.3% vs 0%, P=0.028). In 22 refractory and relapsed PRCA patients, 6 out of 10 (60%) refractory patients and 5 out of 12 (41.7%) relapsed patients achieved remission(table 2). The cumulative rate of CR of CsA alone, CS alone, CS+CsA and other immunosuppressive agents were 27.8%, 6.67%, 66.7%, 10%. The cumulative rate of CR of the combination of CS and CsA was higher than CS alone or CsA alone (66.7% vs 18.2%, P=0.028). The response rate of CS or CsA was higher than other immunosuppressive agents (69.2% vs 20%, P<0.01). The age, gender, the percent of reticulocyte and absolute number of lymphocyte in peripheral blood, and etiology did not influence the response rate. (table 3)Conclusion: Thymoma and LGL are the two common causes of secondary PRCA. CsA and/or CS are effective in treating PRCA.The combination of CS and CsA was more effective in achieving CR than CS alone or CsA alone. It was suggested that we might choose the therapy which contains CsA as the initial induction therapy. Other immunosuppressive agents (tacrolimus or mycophenolate mofetil) was less effective in refractory and relapsed PRCA patients. And it was still needed to explore a more effective therapy for refractory and relapsed PRCA patients. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Progress in the clinical management of pure red cell aplasia and future prospects

Pure red cell aplasia (PRCA) is a type of bone marrow failure syndrome (stem cell failure) and is characterized by severe normocytic, normochromic anemia associated with reticulocytopenia and the absence of erythroblasts in otherwise normal bone marrow. The acquired form of chronic PRCA may present as a primary hematological disease in the absence of any other diseases or secondary to thymoma, lymphoproliferative disorders, infections and collagen vascular diseases or after exposure to various drugs or chemicals. Thus, identifying the cause of PRCA is crucial for the optimal management of this disorder. Idiopathic PRCA and secondary PRCA refractory to treatment of the underlying diseases are both generally treated as an immune-mediated disorder. Most chronic PRCA patients successfully treated with immunosuppressants require maintenance immunosuppressive therapy. Refractoriness to induction immunosuppressive therapy and relapse of anemia may be risk factors for death in idiopathic, thymoma-associated and large granular lymphocyte leukemia-associated PRCA. The major causes of death are infections and organ failure. Standard treatment options for refractory and relapsed PRCA patients and the immunopathophysiology of acquired chronic PRCA merit further research.

Primary acquired chronic pure red cell aplasia refractory to standard treatments: remission with rituximab.

TO THE EDITOR: Pure red cell aplasia (PRCA) is a rare syndrome caused by erythropoietic hypoplasia in the absence of leukocytopenia and thrombocytopenia. It is characterized by severe normocytic and reticulocytopenic anemia, with a normally cellular bone marrow (BM) but devoid of erythroblasts [1]. The acquired form of PRCA is a chronic illness that is often diagnosed in conjunction with a variety of diseases [1], such as lymphoproliferative disorders [2], viral infections, autoimmune hemolytic anemia (AIHA) [3], rheumatologic disorders [4], and allogeneic stem cell transplantation [5]. However, this disorder is rarely diagnosed as an idiopathic condition. Acquired PRCA is managed as an immunologically mediated disease, using immunosuppressive therapy (IST) with corticosteroids and cyclosporine A (CSA) as the treatments of first choice [1]. As alternative and salvage treatment, rituximab has been reported to be highly effective [2,3,4,5]; however, to the best of our knowledge, no case of idiopathic PRCA managed with this agent has been reported. A 63-year-old woman was diagnosed in June 2003 as having PRCA after the discovery of isolated normocytic and reticulocytopenic anemia, the course of which had been insidious and progressive. All other possible underlying causes of erythroblastopenia were ruled out by appropriate investigations (Table 1); other laboratory and radiological evaluations revealed no abnormal findings. The patient had required transfusions of almost 2 units of packed red blood cells (RBC) every 2 to 3 weeks. Once the diagnosis was made, she was started on CSA plus corticosteroids, and soon achieved full recovery from BM erythropoiesis and attained normalization of peripheral blood counts. The patient no longer required transfusions. This was considered complete remission (CR) of PRCA. Therefore, the dosage of CSA was gradually reduced and discontinued. However, there was a progressive loss of response, and CSA was resumed in February 2007 due to a full relapse. The patient achieved a second CR, and the dosage of CSA was carefully tapered. However, the patient experienced progressive chronic renal failure (CRF) in January 2011, which fully resolved after discontinuation of CSA. PRCA recurred soon after, and the patient again required frequent RBC transfusions. When she required approximately 4 RBC units per month, steroids were retried, but without any benefit. Azathioprine was tried without any response. By May 2013, the need for transfusions had reached about 6 RBC units/month, and direct and indirect Coombs blood compatibility tests became positive with the appearance of anti-IgG autoantibody; therefore, the availability of required transfusions became a concern due the difficulty of finding compatible RBC units. In view of this life-threatening complication and a severe hematological condition refractory to all standard treatments for PRCA [1], rituximab was started as a salvage measure at a dose of 375 mg/m2/week for a total of 4 cycles, after the patient gave properly informed consent. Given the lack of experience with rituximab in the setting of primary PRCA, this treatment schedule was derived from that reported as safe and effective in patients with PRCA secondary to lymphoproliferative disorders [2]. After the second dose of rituximab, she exhibited a striking rise in her reticulocyte count and an increase in hemoglobin level. Thus, a third CR was achieved and was maintained during the subsequent 24 months (Fig. 1). In conclusion, the present letter describes a case of acquired chronic primary PRCA of idiopathic origin, refractory to standard measures, with remission on rituximab salvage treatment. To the best of our knowledge, this is the first report of idiopathic PRCA managed with rituximab. In our experience, this agent provided important clinical benefits in an elderly patient with a 12-year PRCA history, during which she had become intolerant/unresponsive to the majority of immunosuppressive agents used in this difficult-to-treat disorder. The course of disease and repeated responses to IST pointed to a possible underlying autoimmune pathogenesis. Although this hypothesis has not been proven by extensive clinical and laboratory evaluations; for this case, rituximab was highly effective in inducing long-lasting remission without any adverse effects.

Diagnosis and management of pure red cell aplasia

Pure red cell aplasia (PRCA) is a type of bone marrow failure syndrome (stem cell failure) and is characterized by severe normocytic, normochromic anemia associated with reticulocytopenia, and the absence of erythroblasts in otherwise normal bone marrow. PRCA may be congenital or acquired, and the acquired form of chronic PRCA may present as a primary hematological disease in the absence of any other diseases or secondary to thymoma, lymphoproliferative disorders, infections, and collagen vascular diseases or after exposure to various drugs or chemicals. The most common types of acquired chronic PRCA in Japan are idiopathic, thymoma-associated and lymphoid neoplasm-associated PRCA. Initial treatment of PRCA includes the cessation of potentially deleterious drugs and careful observation for one month while making efforts to identify the cause of PRCA. Idiopathic PRCA and secondary PRCA refractory to treatment of the underlying diseases are generally treated as immune-mediated disorders. Most chronic PRCA patients successfully treated with immunosuppressants require maintenance immunosuppressive therapy. Thus, identifying the cause of PRCA is crucial for the optimal management of this disorder.

Long-term outcome of patients with acquired chronic pure red cell aplasia (PRCA) following immunosuppressive therapy: a final report of the nationwide cohort study in 2004/2006 by the Japan PRCA collaborative study group.

Immunosuppressive therapy has been employed as the initial treatment for acquired chronic pure red cell aplasia (PRCA), such as idiopathic, thymoma-associated, or large granular lymphocyte (LGL) leukaemia-associated PRCA, which is thought to be immune-mediated. To explore the overall long-term outcome following immunosuppression and to identify the risk factors for death in these disorders, we conducted nationwide surveys in Japan 2004 and 2006, and identified a total of 185 patients with acquired chronic PRCA, including 72 idiopathic, 41 thymoma-associated and 14 LGL leukaemia-associated cases of PRCA for whom data was available. The present study evaluated 127 patients with these three subsets of PRCA. The median overall survival has not yet been reached in idiopathic PRCA. The estimated median overall survival times in patients with thymoma-associated and LGL leukaemia-associated PRCA were 142·1 and 147·8months, respectively. Twenty-two deaths were reported, and the response to induction therapy and relapse of anaemia were found to be associated with death. The major causes of death were infection in seven patients and organ failure in another seven patients. The results suggest that maintenance therapy and the management of infectious complications are crucial for improving the prognosis of chronic PRCA.

English

Anemia in children may arise from a wide variety of pathogenetic mechanisms that include congenital and acquired disorders. Often the diagnostic considerations include disorders that are not seen commonly in adults and lifelong disorders that arise in children and persist throughout life. Consideration of diverse causes of anemia such as red cell membrane disorders, red cell enzymopathies, congenital dyserythropoietic anemias, congenital sideroblastic anemias, and hereditary pure red cell aplasia (Diamond-Blackfan anemia), as well as infectious causes such as parvovirus B19 infection, often is required when diagnosing anemia in an infant or young child. Knowledge of these entities that are important causes of anemia in the pediatric population, including clinical manifestations and laboratory workup, will aid in recognition of the specific disease entities and effective workup of pediatric red cell disorders. Inherited and acquired red cell disorders in children include a diverse group of disorders that include red cell enzyme disorders, red cell membrane disorders, congenital dyserythropoietic anemia, sideroblastic anemia, hemoglobinopathies, and red cell aplasias. Most of these disorders are manifested in the child by anemia with hypoproliferative or hemolytic mechanisms underpinning the development of anemia. Hypoproliferative anemia arises secondary to decreased overall RBC precursors or ineffective erythropoiesis, suggesting an abnormality in bone marrow production or erythroid precursors. Conversely, the anemia may be hemolytic in nature, reflecting abnormalities in RBC structure or biologic function that affect RBC life span and are associated with normal to increased erythropoiesis. Clinical manifestations, RBC characteristics, specific laboratory testing, and bone marrow findings are all useful in trying to classify the cause of the anemia and define a specific disease process. INTRODUCTION: Pure red cell aplasia (PRCA) is an uncommon disorder in which maturation arrest occurs in the formation of erythrocytes. Erythroblasts are virtually absent in bone marrow; however, WBC and platelet production is normal. The anemia due to PRCA is usually normocytic but can be macrocytic. In 1922, Kaznelson recognized that this condition was a different entity from aplastic anaemia, which presents with pancytopenia. The characteristics of PRCA include a severe anemia, a reticulocyte count of less than 1%, and the presence of less than 0.5% mature erythroblasts in the bone marrow. The bone marrow is usually normocellular. The etiology of PRCA is heterogeneous. A congenital form of PRCA was initially described by Joseph in 1936 and by Diamond and Blackfan in 1938. Congenital PRCA is a lifelong disorder and is associated with physical abnormalities. PRCA can be transient and reversible. Transient erythroblastopenia of childhood (TEC) can occur after viral infections. PRCA due to medications is also often reversible when these medications are discontinued. PRCA due to infections is often reversible. In adults, most cases of chronic PRCA are idiopathic, and a cause cannot be established. Secondary PRCA occurs in patients with conditions such as autoimmune disorders, thymomas, hematologic malignancies,

CDR3-independent expansion of Vδ1 T lymphocytes in acquired chronic pure red cell aplasia

Although there exist case reports describing the association of clonal expansion of γδ T cells with chronic acquired pure red cell aplasia (PRCA), there is no consensus regarding whether clonal expansion of γδ T cells are generally found in chronic PRCA. We examined the γδ T cell receptor repertoire in 19 PRCA patients and found that there was a difference in γδ T-cell repertoires between PRCA patients and healthy donors. We observed an increase in Vδ1 γδ T cells and a decrease in Vδ2 T cells in PRCA patients. CDR3δ1 size distribution patterns were skewed in 9 out of 13 PRCA patients examined, although the skewing was also observed in 7 out of 10 healthy individuals. No significant changes were present in CDR3δ1 size distribution between PRCA patients and healthy donors. Moreover, no apparent consensus amino acid motifs were identified in PRCA patients. Expansion of Vδ1 T cells and depletion of Vδ2 T cells are unique features for chronic acquired PRCA but expansion of Vδ1 T cells does not seem to be the consequence of CDR3-dependent selection. We conclude that clonal expansion of Vδ1 T cells is not a general feature for chronic acquired PRCA.

Hemolytic Crisis as the Initial Presentation of Hereditary Spherocytosis Induced by Parvovirus B19 and Herpes Virus Infection in a Patient with the Thalassemia Trait: A Case Report

To the Editor, Human parvovirus B19 (PV-B19) causes erythema infectiosum, hydrops fetalis, and transient aplastic crisis in immunocompromised patients with chronic hemolytic anemia, arthralgia, and chronic pure red cell aplasia [1]. It may also cause autoimmune hemolytic anemia [2] (which presents as aplastic crisis with reticulocytopenia or increased erythropoiesis with reticulocytosis) [3], autoimmune thrombocytopenia/neutropenia, myelodysplastic syndrome, leukoerythroblastosis, hemophagocytic lymphohistiocytosis, and leukemia [1]. Transient aplastic crisis manifests as sudden exacerbation of anemia in patients with chronic hemolytic anemia, with severe reticulocytopenia lasting 7-10 days in the absence of erythroid precursors due to lysis of the precursors by PV-B19 [4]—the hallmark of which is giant pronormoblasts in the bone marrow [5]. Hemolytic crisis in hereditary spherocytosis (HS) is characterized by more pronounced jaundice than that in stable state of HS due to accelerated hemolysis and probable viral infection [6]. Herein we describe a patient that presented with hemolytic crisis as the initial manifestation of HS during PV-B19 infection—in contrast to the expectation of transient aplastic crisis [7]. This condition was attributed to coexistent herpes virus infection. The patient had a low mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) due to the thalassemia trait, which masked spherocytosis. A 15-year-old female was presented for evaluation of anemia. She had a 4-month history of progressive pallor, fatigue, scleral icterus, and dark urine. She has had intractable pallor since nearly 3 years of age Icterus was not noted until four months prior to her presentation to our hospital. Her brother also had pallor without icterus. Physical examination showed pallor, scleral icterus, and hepatosplenomegaly (spleen and liver extended the costal margins by 4 cm and 3 cm, respectively). Laboratory findings were as follows: hemoglobin level: 75 g/L; hematocrit: 24.1%; red blood cell count (RBC):4.11x1012/dL; platelet count: 279 x 109/L; white blood cell count: 7.3 x 109/L: mean corpuscular volume (MCV): 59.5 fL: mean corpuscular hemoglobin concentration MCHC 31.5 g/dl (N: 32.7-35.6 g/dl); mean corpuscular hemoglobin (MCH): 18.5 pg (normal range: 27.2-33.5 pg); red blood cell distribution width: 21% (normal range: 11.8%-14.3%); reticulocyte count: 2.2% (normal range: 0.6%-2.6%). Peripheral blood smear showed anisocytosis, poikilocytosis, hypochromia, and spherocytes. Direct and indirect Coombs tests were negative, and total/indirect bilirubin was 1.68/1.33 mg/dL, haptoglobin was <5.83 mg/dL (normal range: 36-195mg/dL), plasma hemoglobin was 7% (normal: <3), serum lactate dehydrogenase was 254 IU/L, and Hb A2 was 4.37%. Bone marrow aspiration showed erythroid hyperplasia, glucose-6-phosphate dehydrogenase, pyrimidine 5’ nucleotidase, pyruvate kinase, CD 55, and CD 59 evaluation of CD 55, and CD 59 on granulocytes by flow cytometry were normal. Collagen tissue disease markers were negative. Abdominal ultrasonography showed splenomegaly and elevated osmotic fragility. Herpes simplex virus HSV type 1-2 IgM was positive. PV-B19 PCR was 75.3 copies/mL in plasma, based on real-time PCR (normal: negative). The patient was diagnosed as hereditary spherocytosis and thalassemia trait, with coexistent PV-B19 and herpes virus infections.The hemoglobin level was found to have increased spontaneously to 88 g/L and her pallor and scleral icterus were found resolved at the end of in her evaluation made on 46th day of admission At this time blood smear findings and mild indirect hyperbilirubinemia persisted and PV-B19 DNA showed 13 copies and HSV type 1-2 IgM was still positive. Viral serological tests may cross react with each other and we couldn’t perform HSV PCR. But HSV IgG was found to have increased from 6.15 to 113.2 RU/mL on the 46th day of admission and this confirmed that PV-B19 and HSV infected the patient coexistently., The presented patient had mild HS, which manifested first as hemolytic crisis due to herpes virus infection, although infection by other viruses we didn’t test for could not be excluded. Her RBC count was within the lower limits of normal, which is unexpected in a patient with hemolytic anemia and the thalassemia trait. We think the normal RBC and reticulocyte counts, despite erythroid hyperplasia of the bone marrow, were indicative of repressed erythropoiesis due to PV-B19 infection. The presented case highlights the fact that, in the setting of chronic mild hemolytic anemia, patients in hemolytic crisis that have normal reticulocyte and RBC counts should be tested for PV-B19 infection and accompanying other viral infections . Clinicians should be aware that MCH and MCHC are not elevated in HS patients with thalassemia trait. Conflict of Interest Statement None of the authors have any conflicts of interest, including specific financial interests, relationships, and/or affiliations, relevant to the subject matter or materials included.

Rapid Recovery from Chronic PRCA by MSC Infusion in Patient after Major ABO-Mismatched alloSCT

Pure red cell aplasia (PRCA) is a rare complication in recipients of allogenic stem cell from ABO incompatible donors. It is characterized by reticulocytopenia and by an absence of red cell cell precursors in the bone marrow. Despite close isohemagglutinins monitoring and standard immunosupressive treatment in these patients prolong PRCA are still associated with severe transfusion dependence. We report the case of a 31 yr old male patient who underwent HLA-matched ABO-mismatched allo-SCT and developed resistance PRCA despite conventional immunosupressive therapy and prophylaxis cotrasplantation of bone marrow derived MSC at day 0. He responded dramatically to therapy with adipose tissue derived mesenchymal stem cells from HSC donors and continued to be transfusion-independent and AML-disease free. This method of the PRCA therapy of deserves further investigation.

CDR3-Independent Expansion of Vδ1 γδ T Lymphocytes and Depletion of Vδ2 T Cells Are Unique Features in Acquired Chronic Pure Red Cell Aplasia,

Abstract 3429 Background:Idiopathic PRCA and secondary PRCA associated with thymoma and large granular lymphocyte leukemia are major subtypes of adult-onset chronic PRCA. We have previously shown that these types of PRCA are responsive to immunosuppressive therapy but most patients require long-term maintenance immunosuppressive treatment. These results suggest that acquired chronic PRCA is an autoimmune disorder mediated by T lymphocytes and pathogenic T cell clones may be persistently present during remission. We have previously made an interesting observation that a thymoma-associated PRCA patient had an increase of Vd1 gd T cells in blood. We have also reported that recipients of allogeneic hematopoietic stem cell grafts had an oligoclonal expansion of Vd1 gd T cells and that Vd1 gd T clones had cytotoxicity against autologous EBV-transformed B cell line. Thus, gd T cell repertoires may be altered in PRCA patients in response to certain antigens. Objective:In order to clarify the role for gd T cells in the pathogenesis of chronic acquired PRCA, we have examined the gd T cell receptor repertoire in acquired chronic PRCA patients. Materials and Methods:Nineteen PRCA (8 idiopathic, 6 thymoma, 3 LGL-leukemia and 2 SLE) and 107 healthy volunteer donors were included in the study. This study was approved by the Institutional Review Board at Akita University and conducted in accordance with the Declaration of Helsinki. Blood lymphocyte subsets were analyzed by flow cytometry. Clonality of T cells was determined by complementarity-determining region 3 (CDR3) size distribution analysis and junctional sequence was determined by subcloning of PCR products and DNA sequencing. In some experiments, purified gd T cells from PRCA patients were co-cultured with allogeneic erythroid progenitor cells derived from CD34-positive cells in vitro in order to learn whether patient's gd T cells would exert cytotoxic or growth-inhibitory effect on erythroid progenitor cells. Results:The absolute numbers of ab T cells and gd T cells were normal in patients with PRCA, but there were an increase of Vd1 gd T cells and a decrease of Vd2 T cells (Table 1). More than 50% of Vd1 T cells from PRCA patients expressed HLA-DR, while 20 to 30% of those from healthy individuals expressed HLA-DR (Fig. 1). CDR3 size spectratyping revealed that CDR3 size distribution patterns were skewed in 9 out of 13 PRCA patients examined, although skewed CDR3 size distribution patterns were also observed in 7 out of 10 healthy individuals. In order to determine whether a particular Vd1-Jd rearrangement size was selected in PRCA patients, we performed statistical analysis comparing the CDR3 size distribution of 115 Vd1 TCR clones obtained by subcloning of PCR products in 7 PRCA patients versus 7 controls. No significant difference was found between the two groups (p=0.795 by Mann-Whitney test). Moreover, no apparent consensus amino acid motifs were identified in PRCA patients. Although the T cell clone carrying the -YWGIR- sequence in the CDR3d region was detected in 3 PRCA patients, the T cell clone carrying the -YWGIR- sequence was also detected in one healthy donor. Purified gdT lymphocytes from idiopathic PRCA neither showed an inhibitory effect on proliferation nor cytotoxicity against erythroid progenitor cells in vitro.Table 1gd T cell repertoires in PRCA and aplastic anemiaT cellHealthy donors (N=107)PRCA (N=19)Aplastic anemia (N=16)p value: healthy vs. PRCATCRab (/ml)1063.9 ± 33.91256.6 ± 173.9853.5 ± 157.91.000TCRgd (/ml)68.3 ± 4.2142.2 ± 43.527.0 ± 4.41.000Vd1 (/ml)15.6 ± 1.194.0 ± 30.76.6 ± 1.50.000Vd2 (/ml)42.9 ± 3.515.7 ± 5.418.0 ± 4.30.000Vd2/Vd1 ratio4.7 ± 0.60.3 ± 0.15.1 ± 1.50.000Data are expressed as the mean ± SE. [Display omitted] Adjusted p value was calculated by Kruskal-Wallis ANOVA test. Conclusions:Expansion of Vd1 T cells and depletion of Vd2 T cells are unique features for chronic acquired PRCA. Expansion of Vd1 T cells does not seem to be the consequence of CDR3-dependent selection. Depletion of Vd2 T cells may be the result of chronic stimulation, because our previous study has revealed that the numbers of Vd2 T cells show an age-dependent decrease and Vd2 T cells are susceptible to activation-induced cell death (Int J Hematol, in press). Failure to demonstrate the cytotoxicity of gd T cells from a PRCA patient against erythroid progenitor cells suggests that expanded gd T cells are not effector T cells. Disclosures:No relevant conflicts of interest to declare.

Parvovirus-B19 and hematologic disorders.

Parvovirus-B19 (PV-B19) is a member of Parvoviridae, which is one of the smallest DNA viruses. PV-B19-associated diseases usually serve as a good representation of the balance of virus, host response and the immune system. The diseases manifested with PV-B19 are erythema infectiosum, which is common in children, hydrops fetalis, transient pure red cell aplasia in patients with chronic hemolytic anemia, arthralgia - mostly observed in women, and chronic pure red cell aplasia in immunocompromised individuals. Cytopenia (bicytopenia, monocytopenia or pancytopenia) may also accompany the diseases mentioned above. On the other hand, there are many diseases, including neurologic, vasculitic, hepatic, rheumatoid, nephritic, autoimmune, myocardial, and others in which the mechanisms of the diseases are not clear, which may be associated with PV-B19. The virus may manifest with unexpected and unexplained clinical pictures and lead to misdiagnosis. Therefore, hematologic disorders in any unestablished clinical diagnosis should be investigated for PV-B19 infection. However, serologic examination for PV-B19 diagnosis is not sufficient in immunocompromised status. The virus can be determined with polymerase chain reaction (PCR) in the serum or tissue samples. Supportive therapy, blood transfusion and immunoglobulin are the conventional therapeutic interventions for PV-B19 today. Vaccination studies are under examination.