Chronic Autoimmune Thrombocytopenic Purpura Research Articles

Prevalence of Helicobacter pylori in children 2-16 years with chronic Idiopathic thrombocytopenic purpura referred to hematology clinic of Ardabil during 2013-2015

Background: Idiopathic thrombocytopenic purpura (ITP) is the most common autoimmune blood disorder which leads to premature destruction of platelets by producing antibodies using phagocytic cells against antigens of platelets surface especially in the spleen. Recently, several studies have reported the high prevalence of H. pylori infection in adult patients with chronic ITP, but the studies performed in this area have been very limited in children. The purpose of this study is to investigate the prevalence of Helicobacter pylori infection in children with chronic ITP.Methods: In this case- control study, the case sample includes 30 children in the age range of 2-16 years with chronic ITP and control samples includes 90 children in the age range of 2-16 years who are healthy in terms of ITP disease. A questionnaire and a stool sample is prepared for each sample. These samples are examined by the method of ELIZA kit for the presence or absence of antigen H. Pylori. Data analyzed by statistical methods in SPSS.19.Results: Of the total 30 children with chronic ITP who has referred to the haematology ward of the hospital, H.pylori + 16.7%, we had H.pylori + 20% from a total of 90 controls (P=0.68). The average age of the case and control groups were 6.9±2.8 and 6.9±3 years, respectively; there is no a direct relationship between helicobacter pylori infection and sex, drinking water, but there is a statistically significant difference between platelet levels and the prevalence of H Pylori in the case group (p<0.05); however, this difference is not significant in the control group.Conclusions According to a conducted study, Helicobacter pylori infection is not considered as a factor risk in the development of chronic thrombocytopenic purpura in children. So, it is recommended that further studies to be done in different ethnic groups in the world with more samples, especially in the age range of children, so that the role of Helicobacter pylori in the pathogenesis of chronic autoimmune thrombocytopenic purpura can be determined accurately.

Mapping helper T-cell epitopes on platelet membrane glycoprotein IIIa in chronic autoimmune thrombocytopenic purpura

AbstractChronic autoimmune thrombocytopenic purpura (AITP) is associated with autoantibodies specific for platelet membrane components, often including glycoprotein GPIIIa. T helper (Th) cells reactive with GPIIIa, which are capable of driving the autoantibody response, are activated in AITP, and the aim here was to map the epitopes that they recognize. Peripheral blood mononuclear cells (PBMCs) were obtained from 31 patients with AITP and 30 control donors and stimulated with a panel of 86 overlapping synthetic 15-mer peptides spanning the complete sequence of GPIIIa. One or more peptides elicited recall proliferation by PBMCs from 28 of the patients, and, typically, multiple sequences were stimulatory. In contrast, responses in healthy control donors were rare (chi-square test = 115.967; P ≤ .001). It was confirmed that the proliferating PBMCs from patients were cells of the CD3+CD4+ helper phenotype that were MHC class II restricted. Despite variation between different cases of AITP, particular sequences were commonly recognized with PBMCs from 24 patients (77%) responding to 1 or more of the 4 most dominant peptides. Mapping such dominant autoreactive helper epitopes is the first step in the development of new approaches to the treatment of AITP, based on the use of peptides to tolerize Th cells specific for platelet glycoproteins.

Successful treatment with T depleted autologous peripheral blood stem cell transplantation of refractory chronic autoimmune thrombocytopenic purpura

Autoimmune thrombocytopenia (AITP) is a disorder due to specific platelet auto-antibodies directed against platelet surface glycoproteins. AITP in adults is usually chronic, idiopathic and frequently refractory to conventional treatments. Myelo- and immuno-suppressive chemotherapy followed by autologous peripheral blood stem cell (PBSC) transplantation is an experimental approach for severe chronic refractory AITP. We report a case of a woman with AITP, refractory to the conventional therapy, submitted to T-cell-depleted autologous PBSC transplantation, which obtained long term stable response on platelet count. We deem that the positive outcome of our patient depends on T-cells depletion of the graft, which reduces autoreactive T clones.

Cyclosporin A as an Immunosuppressive Treatment Modality for Patients with Refractory Autoimmune Thrombocytopenic Purpura after Splenectomy Failure

The treatment of autoimmune thrombocytopenic purpura (AITP) remains unsatisfactory in patients refractory to first-line management such as corticosteroid therapy and/or splenectomy. Patients with refractory AITP usually require unacceptably high doses of corticosteroids to maintain a safe platelet count. Immunosuppressive treatment with cyclosporin A (CsA) is a relatively new treatment modality, and no large studies of this drug have been conducted. We used CsA in 6 patients with refractory AITP who had platelet counts of less than 20 x 10(9)/L without any therapy or who had evidence of subcutaneous and mucosal bleeding. All 6 patients had undergone splenectomy. When CsA therapy was begun, 5 of the patients were receiving methylprednisolone (MP) at a daily dose of 32 mg or greater. During the following months, the MP dosage was tapered, or the drug was withdrawn. Three patients achieved a complete remission (CR), whereupon CsA treatment was gradually discontinued. Two of these 3 patients later relapsed, but both responded to an additional course of CsA and achieved a second CR. The remaining 3 patients achieved a partial remission (PR). One patient, a woman with an AITP history of more than 30 years, obtained a stable PR with a platelet count substantially greater than 20 x 10(9)/L, which was successfully maintained by low doses of CsA and MP. The most frequent side effect of CsA therapy in our patients was a painful edema of the lower extremities. Our experience shows that CsA is a safe and effective treatment option for patients with refractory (chronic) AITP. It may be given at a low dose as maintenance therapy, and remissions may be sustained even after the drug has been discontinued.

What Is New Related to Helicobacter pylori Infection in Children and Teenagers?

Helicobacter pylori infection is a common bacterial infection for humans, and the organism is the most prevalent gastric microbial pathogen. However, the major route of transmission remains poorly understood. The outcome of chronic H pylori infection varies from asymptomatic gastritis to peptic ulceration and gastric malignancies. Recently, H pylori has been associated with the development of extradigestive disorders, including refractory iron-deficiency (sideropenic) anemia and chronic autoimmune thrombocytopenic purpura. Virulence factors of H pylori and host genetic factors are both considered important determinants of disease outcome. Multiple tests, including novel noninvasive approaches, are available for establishing the presence of H pylori infection, but there is still little consensus about which study should be performed and in what clinical setting. Eradicating H pylori uses combination therapy, including a proton pump inhibitor and 2 antibiotics taken twice daily for 7 to 14 days. Antibiotic resistance is a growing and serious problem that interferes with the success of eradication therapy. Testing and eradication therapy for H pylori are currently recommended only for the subset of infected persons in whom the disease sequelae are proven or highly suspected.

Intravenous Immunoglobulin for Autoimmune Thrombocytopenic Purpura

Severe autoimmune thrombocytopenic purpura is now commonly treated with high doses of intravenous immunoglobulins (IVIGs). Twenty-four years after this treatment was first demonstrated to be effective, several questions remain to be resolved. We review here current knowledge concerning the frequency and type of side effects and the likely mechanism of action of IVIGs. We suggest that the currently recommended dose of IVIG (2 g/kg) could be halved, that the total dose of IVIG should be administered as a single infusion, that nonresponders could be provided another equal dose on day 3, and that IVIG plus prednisolone should be considered the gold standard for treatment of the most severe forms of the disease. Treatment with anti-D immunoglobulin could be proposed as an alternative if the results recently obtained with high doses (75 μg/kg) are confirmed. Finally, because IVIG has only a transient effect, it cannot be considered a curative treatment for patients with chronic autoimmune thrombocytopenic purpura.

Cyclosporin A as Immunosuppressive Treatment Option for Patients with Refractory Auto-Immune Thrombocytopenic Purpura.

The treatment of auto-immune thrombocytopenic purpura (AITP) remains unsatisfactory in patients refractory to first-line management such as corticosteroids and/or splenectomy. Those patients usually require unacceptably high doses of corticosteroids to maintain a safe platelet count and thus have refractory AITP. Relativelly new immunosupressive treatment modality is cyclosporin A (CsA) and no large studies involving these drug have been conducted. We treated 7 refractory AITP patients with CsA. Their platelet count were without any therapy below 20x109/L and mostly they had signs of subcutaneous and mucosal bleeding. In 6/7 patients splenectomy was performed earlier. In order to maintain »safe« platelet count, they all needed methylprednisolon (MP), at least 32 mg/daily. So at the time treatment with CsA began, all patients were on MP. During next months MP dosage was tapered or withdrew, according to patients platelet count and treatment efficacy. At the endpoint, in 4/7 patients complete remission (CR) was achieved and later CsA was slowly ceased. 3/7 patients are currently in partial remission (PR) of the disease. Also one of them who has more than 30 years history of the disease is in stable PR, on low dose CsA and low dose MP maintanance therapy. Her platelet count is well above 20x109/L. Among CsA treatment related side effects painful lower limb edema was most frequent.Based on our experience we suggest, that CsA should be recommended in refractory (chronic) AITP patients, because it shows long-term efficacy and good safety profile and is able to sustain remission at low doses or even after CsA discontinuation.

Intravenous immunoglobulin and autoimmune thrombocytopenic purpura: 22 years on.

Autoimmune thrombocytopenic purpura is now commonly treated with high doses of intravenous immunoglobulins. Twenty-two years after this treatment was first shown to be effective, several questions remain. We review here current knowledge concerning the frequency and type of side-effects and the probable mechanism of action of intravenous immunoglobulins. We suggest that the currently recommended dose of intravenous immunoglobulins (2 g/kg body weight) could be halved, that the total dose of intravenous immunoglobulins should be administered as a single infusion, that non-responders could be given another equal dose on day 3, and that intravenous immunoglobulins plus prednisolone should be considered as the gold standard for treatment of the most severe forms of the disease. Finally, as intravenous immunoglobulins have only a transient effect, they cannot be considered as a curative treatment for patients with chronic autoimmune thrombocytopenic purpura.

Anti-D initially stimulates an Fc-dependent leukocyte oxidative burst and subsequently suppresses erythrophagocytosis via interleukin-1 receptor antagonist

AbstractPrevious results have demonstrated that anti-D therapy in children with chronic auto-immune thrombocytopenic purpura (AITP) induced a significant increase in several pro- and anti-inflammatory plasma cytokines within 2 hours of administration. To investigate the biologic basis of these early in vivo responses, we developed a flow cytometric assay to measure Fc-dependent responses of human peripheral leukocytes with fluorescently labeled and anti-D–opsonized red blood cells (RBCs). When anti-D–opsonized RBCs were incubated with peripheral blood leukocytes, the earliest detectible event observed was a significant oxidative burst in both monocytes (P < .05) and granulocytes (P < .0001), characterized by the production of hydrogen peroxide (H2O2), peroxynitrite (ONOO–), superoxide (O –2), and hydroxyl (OH) by 10 minutes which declined by 1 hour. By 2 hours, the opsonized RBCs were phagocytosed, particularly by granulocytes (P < .001), but the phagocytosis subsequently declined by 6 hours of incubation. The decline in phagocytosis was correlated with a significant production of interleukin-1 receptor antagonist (IL1ra) by both monocytes (P = .036) and granulocytes (P = .0002) within 4 hours. None of these events occurred if the RBCs were coated with anti-D F(ab)′2 fragments. When recombinant IL1ra was titrated into the assay, phagocytosis of the opsonized RBCs was significantly inhibited (P = .002). Taken together, these results suggest that at least one mechanism of action of anti-D is via the production of the anti-inflammatory cytokine IL1ra which can negatively regulate the ability of leukocytes to phagocytose opsonized cells.

Misdiagnosis of chronic thrombocytopenia in childhood.

Children ultimately diagnosed with nonimmune chronic thrombocytopenia are often referred to pediatric hematology clinics with a provisional diagnosis of autoimmune thrombocytopenic purpura (AITP). The authors' aim was to establish in these patients the features characterizing the mechanism of thrombocytopenia. The authors performed a retrospective review of the case records of seven children (three boys and four girls, aged 5 months to 7 years) with misdiagnosed chronic AITP referred to a single pediatric hematology center between 1990 and 2000. In the seven children, the suspected diagnosis on referral was AITP and the final diagnosis was inherited thrombocytopenia. Abnormalities of platelets and/or leukocyte morphology were present in all of them. Other features suggestive of inherited thrombocytopenia included a history of familial thrombocytopenia (2/7), failure of steroids and/or intravenous immunoglobulins to raise the platelet count to normal levels (5/7), and moderate increase of Indium-111 platelet turnover in the two patients tested. Platelet-associated IgG (PaIgG) was above the normal threshold in the four children tested; the direct monoclonal antibody immobilization of platelet antigens (MAIPA) test was negative in the four children tested and the serum test was positive in two boys. Bone marrow examination revealed either a normal (4/7) or an elevated (3/7) number of megakaryocytes. Family history and blood cell morphology analysis in experienced hands are the first steps in discriminating AITP from inherited thrombocytopenia in children with isolated chronic thrombocytopenia. In contrast, bone marrow examination and search for specific autoantibodies using the MAIPA test are of little help. An isotopic platelet life span study, when available, should be performed before considering splenectomy to exclude the diagnosis of inherited thrombocytopenia, especially when steroids and/or IgG IV administration failed to raise the platelet count.

T cell and cytokine abnormalities in patients with autoimmune thrombocytopenic purpura

Autoimmune thrombocytopenic purpura (AITP) is a bleeding disorder in which autoantibodies are directed against an individual’s own platelets, leading to enhanced clearance through Fc receptor (R)-mediated phagocytosis by macrophages residing in the reticuloendothelial system, particularly in the spleen. Although the immunopathogenesis of the disease is autoantibody-mediated, there is now substantial evidence that suggest that the antiplatelet autoantibodies are under the control of T helper (Th) cells and the cytokines that they produce. This review will summarize the recent literature regarding abnormal Th cell reactivities and cytokine secretion in AITP. Reviews of the earlier literature regarding cell mediated immunity in chronic AITP have been published [ Semple and Freedman. Autoimmunity 13 (1992) 311; Semple and Freedman. Transfus. Med. Rev. 9 (1995) 327]. Understanding the immune mechanisms controlling cell-mediated mechanisms is vital for developing antigen specific immunotherapies to treat the disease.

Effects of B7-blocking agent and/or CsA on induction of platelet-specific T-cell anergy in chronic autoimmune thrombocytopenic purpura

Chronic autoimmune thrombocytopenic purpura (AITP) is characterized by platelet-specific autoantibody production that is influenced by enhanced antiplatelet T-helper cell reactivity. Costimulatory signals are absolutely required for T-cell activation and play key roles in the decision between tolerance and immunity. In this study we cultured T cells isolated from patients with chronic AITP to investigate the effects of the B7-blocking agent cytologic T-lymphocyte-associated antigen 4-immunoglobulin (CTLA4-Ig), and cyclosporin A (CsA), alone or in combination, on induction of platelet-specific T-cell anergy. The data showed that in most cases CTLA4-Ig and/or CsA could induce tolerance toward platelet antigens based on anergy. It could be overcome by stimulation with unrelated antigens, demonstrating its platelet specificity. The anergy is associated with lack of interleukin 2 (IL-2) and withheld by exogenous IL-2, emphasizing the pivotal role of IL-2 suppression in the induction of platelet-specific anergy. We also prospectively evaluated the efficacy of CsA therapy in patients with refractory AITP and observed that the response to CsA treatment in vivo was associated with the inhibiting sensitivity of platelet-reactive T cells to CsA in vitro. This suggests that the sensitivity of T cells to CsA in vitro could serve as a reliable parameter in predicting the efficacy of CsA for patients with refractory AITP. CTLA4-Ig may become a promising new therapeutic agent for the treatment of chronic AITP, and the combination of CTLA4-Ig and CsA would be a more powerful strategy for the management of refractory AITP.

Long-term follow-up of chronic autoimmune thrombocytopenic purpura refractory to splenectomy: a prospective analysis.

Splenectomy remains the most effective treatment of chronic autoimmune idiopathic thrombocytopenia (ITP) (i.e. of > 6 months duration). Treatment of patients refractory to splenectomy (with absence of response or relapse after initial response) is difficult, and their long-term outcome is not well known. Over a 10-year period, 183 patients with chronic ITP were splenectomized including 158 adults and 25 children (</= 15 years). Forty-seven of them, who were refractory to this treatment, were prospectively followed up for 5-15 years (median 7.5 years). Twelve of them, with moderate thrombocytopenia, remained untreated, and 35 were treated by a median of two regimens (range 1--6), to which 27 responded. Thirty-six (77%) of the refractory cases reached platelet counts durably > 100 x 10(9)/l, nine of them without treatment and 27 of them with low-dose steroids or azathioprine; six (13%) remained moderately thrombocytopenic (35 x 10(9)/l to 100 x 10(9)/l platelets); the last five patients, without response to any treatment (up to six regimens), remained severely thrombocytopenic (platelets < 20 x 10(9)/l), and three of them died from bleeding. Twenty-seven (57%) of the 47 refractory cases required at least one hospitalization, in the majority of cases for intravenous immunoglobulin (IVIg) infusions. Seven of the refractory cases occurred in children. Six of them subsequently reached platelet counts > 100 x 10(9)/l, but one died from bleeding. Our findings confirm the overall favourable long-term prognosis of chronic ITP refractory to splenectomy.

Immune pathophysiology of autoimmune thrombocytopenic purpura

Chronic autoimmune thrombocytopenic purpura (AITP) is an immune-mediated, bleeding disorder in which platelets are opsonized by autoantibodies and prematurely destroyed by phagocytic cells in the reticuloendothelial system. It is classed as an organ-specific autoimmune disease primarily mediated by immunoglobulin G (IgG) autoantibodies and its etiology appears to be similar to that observed for other organ-specific autoimmune diseases. Th1 cells are important in the process, and the costimulation of Th1 cells and B cells takes place in a cytokine milieu that is reminiscent of a proinflammatory process. Chronic AITP has classically been treated with nonspecific, immunosuppressive regimens (e.g., steroids). One of the most significant developments in the treatment of AITP in the last 20 years has been the use of intravenous immunoglobulin (IVIg) and anti-D preparations. These treatments confer benefit to patients with AITP by significantly raising platelet counts. Despite this, their exact mechanisms of action remain elusive. This review focuses on cell-mediated and cytokine abnormalities within AITP, and presents data related to the mechanism of action of anti-D.

Oral vaccination with autologous platelets in chronic autoimmune thrombocytopenic purpura

Idiopathic thrombocytopenic purpura (ITP) is a common disease of autoimmune mechanism in which nearly 40% of patients need a third-line treatment after steroids and splenectomy failure. Due to the variable results of the multiple therapeutic modalities in refractory patients it is necessary to develop a more effective treatment. Following previous assays of immunotolerance with the administration of ‘oral vaccines’, we propose a therapeutic protocol in chronic ITP patients with autologous cryopreserved or liophilized platelets administered in enteric capsules. The procedure is theoretically feasible and technically easy and does not need the isolation of the specific antigen target of the autoantibodies in each particular case.

Lack of relevance of the acetylator status on dapsone response in chronic autoimmune thrombocytopenic purpura.

Dapsone provides an alternative treatment for patients with chronic autoimmune thrombocytopenic purpura (AITP) who had inadequate response to conventional therapy. However, the efficacy of this treatment is achieved in only 50% of patients. Dapsone is partly metabolized by the polymorphic N-acetyltransferase 2% and 50% of Caucasian patients show a genetically determined slow acetylator phenotype. The aim of our study was to investigate the influence of the acetylator status on dapsone efficacy in patients with chronic AITP. Nineteen caucasian adults with chronic AITP, previously treated by dapsone, were included in the study. Acetylator phenotype was determined by using a caffeine urinary test. Among the fourteen fast acetylator patients, eight patients exhibited positive response to dapsone and six patients did not. Among the five slow acetylator patients, one patient displayed a positive response to dapsone. Comparison of data by using the Fisher's exact test did not reach statistical significance. Our results do not support a relationship between dapsone efficacy and acetylator status in adults with chronic AITP.

Lack of relevance of the acetylator status on dapsone response in chronic autoimmune thrombocytopenic purpura

Dapsone provides an alternative treatment for patients with chronic autoimmune thrombocytopenic purpura (AITP) who had inadequate response to conventional therapy. However, the efficacy of this treatment is achieved in only 50% of patients. Dapsone is partly metabolized by the polymorphic N-acetyltransferase 2% and 50% of Caucasian patients show a genetically determined slow acetylator phenotype. The aim of our study was to investigate the influence of the acetylator status on dapsone efficacy in patients with chronic AITP. Nineteen caucasian adults with chronic AITP, previously treated by dapsone, were included in the study. Acetylator phenotype was determined by using a caffeine urinary test. Among the fourteen fast acetylator patients, eight patients exhibited positive response to dapsone and six patients did not. Among the five slow acetylator patients, one patient displayed a positive response to dapsone. Comparison of data by using the Fisher's exact test did not reach statistical significance. Our results do not support a relationship between dapsone efficacy and acetylator status in adults with chronic AITP. Am. J. Hematol. 62:251–252, 1999. © 1999 Wiley-Liss, Inc.

Allele Frequencies of Human Platelet Antigen 1, 2, 3, and 5 Systems in Patients with Chronic Refractory Autoimmune Thrombocytopenia and in Normal Persons

Background and Objectives: Chronic refractory autoimmune thrombocytopenic purpura (AITP) is an autoimmune disorder due to autoantibodies against platelet glycoproteins (GP). Human platelet alloantigenic (HPA) systems are distributed to different platelet GPs. We carried out genotyping of diallelic HPA–1, –2, –3, and –5 systems to clarify potential associations between HPA alleles and the development of chronic refractory AITP. Patients and Methods: DNA was isolated from 33 unrelated German patients with chronic refractory AITP and from 80 randomly selected German blood donors to determine the phenotype and allele frequencies for the HPA–1, –2, –3, and –5 systems. Fragments carrying the polymorphic sequences corresponding to those alleles were amplified by the polymerase chain reaction and further characterized by restriction analysis. Results: Whereas HPA–1, –3, and –5 allele frequencies were identical in 33 patients with chronic refractory AITP and in controls, HPA–2 allele frequencies showed a statistically significant difference (p = 0.017). In our group of patients, the HPA–2a allele frequency was 100%, but HPA–2b was not seen. In contrast, the allele frequency of HPA–2a in the control group was 92% (n = 147), and in HPA–2b it was 8% (n = 13). Conclusion: This study suggests an association between the HPA–2a allele and chronic refractory AITP. The HPA–2a allele may be involved in the formation of an AITP–specific autoepitope.

Allele Frequencies of Human Platelet Antigen 1, 2, 3, and 5 Systems in Patients with Chronic Refractory Autoimmune Thrombocytopenia and in Normal Persons

Abstract Background and Objectives: Chronic refractory autoimmune thrombocytopenic purpura (AITP) is an autoimmune disorder due to autoantibodies against platelet glycoproteins (GP). Human platelet alloantigenic (HPA) systems are distributed to different platelet GPs. We carried out genotyping of diallelic HPA‐1, ‐2, ‐3, and ‐5 systems to clarify potential associations between HPA alleles and the development of chronic refractory AITP. Patients and Methods: DNA was isolated from 33 unrelated German patients with chronic refractory AITP and from 80 randomly selected German blood donors to determine the phenotype and allele frequencies for the HPA‐1, ‐2, ‐3, and ‐5 systems. Fragments carrying the polymorphic sequences corresponding to those alleles were amplified by the polymerase chain reaction and further characterized by restriction analysis. Results: Whereas HPA‐1, ‐3, and ‐5 allele frequencies were identical in 33 patients with chronic refractory AITP and in controls, HPA‐2 allele frequencies showed a statistically significant difference (p = 0.017). In our group of patients, the HPA‐2a allele frequency was 100%, but HPA‐2b was not seen. In contrast, the allele frequency of HPA‐2a in the control group was 92% (n = 147), and in HPA‐2b it was 8% (n = 13). Conclusion: This study suggests an association between the HPA‐2a allele and chronic refractory AITP. The HPA‐2a allele may be involved in the formation of an AITP‐specific autoepitope.

The response to high-dose intravenous immunoglobulin or steroids is not predictive of outcome after splenectomy in adults with autoimmune thrombocytopenic purpura.

The response to high-dose intravenous immunoglobulin (IVIg) was recently reported to be predictive of outcome after splenectomy in patients with autoimmune thrombocytopenic purpura (AITP). We analysed the records of 75 adults with chronic AITP who received IVIg and subsequently underwent splenectomy. There was no significant difference in the response rate to splenectomy according to whether or not patients had responded to IVIg (81% v 67%, P = 0.36). Age, the time from diagnosis to splenectomy, and the response to steroids were also not significantly associated with outcome after splenectomy. These results indicate that the response to IVIg or steroids is not predictive of the efficacy of splenectomy.