scholarly journals Antiplatelet antibody-induced thrombocytopenia does not correlate with megakaryocyte abnormalities in murine immune thrombocytopenia

2018 ◽  
Vol 88 (1) ◽  
pp. e12678 ◽  
Author(s):  
L. Guo ◽  
R. Kapur ◽  
R. Aslam ◽  
K. Hunt ◽  
Y. Hou ◽  
...  
Blood ◽  
2011 ◽  
Vol 118 (24) ◽  
pp. 6403-6406 ◽  
Author(s):  
Andrew R. Crow ◽  
Sara J. Suppa ◽  
Xi Chen ◽  
Patrick J. Mott ◽  
Alan H. Lazarus

Abstract To definitively determine whether the neonatal Fc receptor (FcRn) is required for the acute amelioration of immune thrombocytopenia (ITP) by IVIg, we used FcRn-deficient mice in a murine ITP model. Mice injected with antiplatelet antibody in the presence or absence of IVIg displayed no difference in platelet-associated IgG between FcRn deficient versus C57BL/6 mice. FcRn-deficient mice treated with high-dose (2 g/kg) IVIg or a low–dose (2 mg/kg) of an IVIg-mimetic CD44 antibody were, however, protected from thrombocytopenia to an equivalent extent as wild-type mice. To verify and substantiate the results found with FcRn-deficient mice, we used β2-microglobulin–deficient mice (which do not express functional FcRn) and found that IVIg or CD44 antibody also protected them from thrombocytopenia. These data suggest that for both high-dose IVIg as well as low-dose CD44 antibody treatment in an acute ITP model, FcRn expression is neither necessary nor required.


2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ke Zhang ◽  
Zhenfeng Dai ◽  
Runzhe Liu ◽  
Fang Tian ◽  
Xi Liu ◽  
...  

Immune thrombocytopenia (ITP) is a common acquired autoimmune disease, and thrombopoietin (TPO) is an important cytokine that regulates the production of megakaryocytes and platelets. We have identified a biologically active component, icaritin, from a Chinese herba epimedii extract. Icaritin promotes platelet production and regulates T cell polarization, but its mechanism is not clear. In this study, the BALB/c mouse model of ITP was established by injection of an antiplatelet antibody every other day for seven total times. The antiplatelet sera were derived from guinea pigs immunized with the platelets of BALB/c mice. Mice with ITP were treated with icaritin at low, moderate, or high doses of 4.73, 9.45, and 18.90 mg/kg, respectively, for fourteen consecutive days. The present study shows that icaritin can significantly increase peripheral blood platelet counts and thrombocytocrit, increase the TPO level in serum, attenuate splenomegaly, and reduce the abnormal proliferation of megakaryocytes in the spleen and bone marrow. Icaritin can also downregulate the expression of bone marrow TPO, myeloproliferative leukemia virus oncogene (MPL), and p-Stat3. Our results suggest that icaritin can significantly improve the health of mice with ITP via possible downregulation of p-Stat3 expression in the JAK2/Stat3 phosphorylation signaling pathway and regulation of bone marrow TPO/MPL metabolism.


Blood ◽  
2006 ◽  
Vol 109 (6) ◽  
pp. 2470-2476 ◽  
Author(s):  
Rong Deng ◽  
Joseph P. Balthasar

Abstract The present work evaluated antibody-coated liposomes as a new treatment strategy for immune thrombocytopenic purpura (ITP) through the use of a mouse model of the disease. Effects of antimethotrexate antibody (AMI)–coated liposomes and intravenous immunoglobulin (IVIG)–coated liposomes (15, 30, 60 μmol lipid/kg) were compared with the effects of IVIG (0.4, 1, 2 g/kg) and anti–red blood cell (anti-RBC) monoclonal antibody immunotherapy (TER119, 5, 15, 25, and 50 μg/mouse) on MWReg30-induced thrombocytopenia. Each treatment was found to attenuate thrombocytopenia in a dose-dependent manner and, consistent with previous work, IVIG was found to increase antiplatelet antibody clearance in a dose-dependent manner. TER119 demonstrated greater effects on thrombocytopenia relative to other therapies (peak platelet counts: 224% ± 34% of initial platelet counts for 50 μg TER119/mouse versus 160% ± 34% for 2 g/kg IVIG, 88% ± 36% for 60 μmol lipid/kg AMI-coated liposomes, and 80% ± 25% for 60 μmol lipid/kg IVIG-coated liposomes). However, the effects of TER119 were associated with severe hemolysis, as TER119 decreased RBC counts by approximately 50%. The present work demonstrated that antibody-coated liposomes attenuated thrombocytopenia in this model at a much lower immunoglobulin dose than that required for IVIG effects and, in contrast with TER119, antibody-coated liposomes increased platelet counts without altering RBC counts.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2250-2250
Author(s):  
Marc Michel ◽  
Daniel Adoue ◽  
Stéphane Cheze ◽  
Paul Coppo ◽  
Soraya Leclerc-Teffahi ◽  
...  

Abstract Immune Thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated low platelet count (<100x109/L) with a variable risk of bleeding. The prevalence of ITP in France is 25/100000. While drug therapy is indicated in patients with platelet count less than 30x109/L and or with bleeding symptoms, discussions remain about therapeutic strategy to be implemented. The SATURNE study aimed to describe the current therapeutic management of adult ITP patients, to focus on TPO-RAs treated patients, and to assess changes in real life treatment strategy since TPO-RAs' approval. This study was carried out in referral and non-referral centersby hematologists and internists from hospitals or clinics in France. Enrolled patients were adults suffering from persistent (3 to 12 months after diagnosis) or chronic (>12 months) ITP. Patients with a newly diagnosed ITP (<3 months) and patients with secondary ITP (viral infection, lupus, etc.) were excluded. Data were collected online by investigators through an eCRF at inclusion (M0). A subgroup of patients initiating a TPO-RAs treatment during the study period was followed up at M3, M6, M12, M18 and M24. Only M0 data are presented in this abstract as interim analysis. Overall, 48 investigators included 333 patients (278 with chronic ITP and 55 with persistent ITP) over a 19 months period (2012 to 2013). Figure 1 displays the main characteristics including comorbidities and laboratory tests performed at diagnosis. Half ofthe patients (53%) had bleeding manifestations at ITP diagnosis; 10% at time of inclusion. ITP was mainly diagnosed by a hematologist (53%) or an internist (32%) and less frequently by a general practitioner (11%). Patients completed a median of 2 treatment lines before entering the study. Figure 2 shows treatment-lines distribution according to the ITP phase. Most patients had been treated with corticosteroids ± intravenous immunoglobulin (IVIG) (83%) as 1st line treatment. Rituximab was the preferred 2nd line option, far prior to splenectomy (44% vs 14%). A total of 144 patients (123 chronic/ 21 persistent ITP) received TPO-RAs (39% romiplostim/ 33% eltrombopag / 15% both / 13% non specified): 6%, 20%, 34%, 28% and 12% respectively as a 1st line treatment, 2nd, 3rd, 4th, 5th and beyond. At inclusion 75% were still on TPO-RAs. Recently diagnosed patients received 2nd line TPO-RAs in higher proportions: 40% (of 46 patients diagnosed <2 years) vs 15% (of 65 patients diagnosed 2-5 yrs ago) and 7% (of 72 patients diagnosed >5 yrs). TPO-RAs became the 3rd line most used treatment (over 76% for diag. <2 yrs). In parallel, the use of splenectomy decreased from 31% (diag. >5 yrs) to 9% (<2 yrs) in 2nd line, and from 16% to 5% in 3rd line. TPO-RAs treated patients had a more severe ITP, in particular at diagnosis. More patients in this group showed platelet counts less than 30.109/L (71% vs 51%, p<0.0001 at diagnosis / 23% vs 10%, p<0.001 at inclusion), and bleeding manifestations (64% vs 44%, p<0.001 at diagnosis/12% vs 8%, p=0.24 at inclusion). They received an average of 3.2 lines of treatment (against 1.7 in TPO-RAs' non-treated patients, p<0.0001). The SATURNE study supports epidemiological trends observed in current practice in terms of patients and ITP characteristics, and provides current data on comorbidities. The results highlight the increasing use of TPO-RAs as 2nd and 3rd lines for ITP treatment and the decrease of splenectomy use over time. Initiated in 2012, respectively 1 and 2 years after eltrombopag and romiplostim approval, the SATURNE study points out the changes of the management of adult ITP in France. Table 1. N=333 Age 57 ± 20yr Women 190 (57%) Main ITP characteristics Chronic/Persistent ITP 278 (84%)/55 (16%) Mean ITP duration* 6 ±8yr Platelet count* - diagnosis - inclusion 33±31.109/L 100±83.109/L Hemorrhagic manifestations- diagnosis- baseline 176 (53%) 32 (10%) White blood cell* 8±3.109/L Hemoglobin* 14±5g/dl Globular volume* 90±6fl Comorbidities since ITP diagnosis At least once 36% Hypertension 17% Diabetes 8% Benign/malignant tumors 8% Cardiovascular disease 6% Diagnostic tests performed at ITP onset Viral serology tests 96% Blood smear 93% Blood coagulation 93% Marrow aspirate 78% Antiplatelet antibody 52% ITP treatment (at least once since diagnosis all lines combined) Corticosteroids and/or IVIG 275 (83%) Rituximab 146 (44%) TPO-RAs- eltrombopag- and/or romiplostim 144 (43%) 69 (48%) 78 (54%) Splenectomy 59 (18%) *mean ± SD Figure 1. Figure 1. Disclosures Michel: Roche: Research Funding; AMGEN: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; GSK: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Adoue:GSK: Other: Symposium presentations; AMGEN: Other: Symposium presentations; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; OCTAPHARMA: Other: Symposium presentations; LFB: Other: Symposium presentations; PFIZER: Other: Symposium presentations; ACTELION: Other: Symposium presentations. Cheze:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Coppo:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees. Leclerc-Teffahi:Novartis: Employment. Fernandes:Novartis: Other: CRO. Texier:Novartis: Other: CRO.


Blood ◽  
2002 ◽  
Vol 100 (6) ◽  
pp. 2087-2093 ◽  
Author(s):  
Ryan J. Hansen ◽  
Joseph P. Balthasar

Experiments were conducted to investigate the effects of intravenous immunoglobulin (IVIG) in a rat model of immune thrombocytopenia (ITP). Rats were pretreated with 0 to 2 g/kg IVIG and then challenged with an antiplatelet antibody (7E3, 8 mg/kg). IVIG effects on 7E3-induced thrombocytopenia and on 7E3 pharmacokinetics were determined. IVIG pretreatment led to significant changes in the degree and time-course of 7E3-induced thrombocytopenia (P = .031). Nadir percent platelet counts were 121% to 279% greater in animals treated with IVIG (0.4-2 g/kg) than in animals receiving 7E3 alone. IVIG treatment also led to dose-dependent increases in 7E3 clearance (P < .001), with more than 2-fold increases in 7E3 clearance seen following the highest dose of IVIG. In vitro experiments showed that IVIG effects on platelet count are not likely due to anti-idiotypic inhibition of 7E3-platelet binding and that IVIG did not directly bind to 7E3. Consequently, IVIG-7E3 binding cannot explain the increase of 7E3 clearance following IVIG treatment. We propose that the observed increase in 7E3 clearance with IVIG therapy is due to saturation of the FcRn salvage receptor for IgG. The importance of the effect of IVIG on 7E3 clearance to the prevention of thrombocytopenia in these animals is unclear at present; nonetheless, these data provide experimental support for a new mechanism of IVIG action in ITP (ie, IVIG-mediated increases in antiplatelet antibody elimination). This model of ITP will be useful for further investigations of IVIG mechanism of action and for development of new therapies for ITP.


Blood ◽  
2014 ◽  
Vol 124 (18) ◽  
pp. 2858-2866 ◽  
Author(s):  
Sylvain Audia ◽  
Marzia Rossato ◽  
Kim Santegoets ◽  
Sanne Spijkers ◽  
Catharina Wichers ◽  
...  

Key Points Human splenic TFH expansion during ITP participates in B-cell differentiation and antiplatelet-antibody production. IL-21 and CD40 are key TFH molecules that could be promising targets in the treatment of ITP.


Blood ◽  
2003 ◽  
Vol 101 (9) ◽  
pp. 3708-3713 ◽  
Author(s):  
Seng Song ◽  
Andrew R. Crow ◽  
John Freedman ◽  
Alan H. Lazarus

Intravenous immunoglobulin (IVIG) is used to treat immune thrombocytopenia resulting from a variety of autoimmune and nonautoimmune diseases such as idiopathic thrombocytopenic purpura (ITP), heparin-induced thrombocytopenia, and posttransfusion purpura. IVIG is a limited resource and although considered safe, may nevertheless carry some risk of transferring disease. Its high cost makes monoclonal antibodies, capable of mimicking the clinical effects of IVIG, highly desirable. We show here, using a murine model of ITP, that selected monoclonal antibodies can protect against thrombocytopenia. SCID mice were pretreated with 1 of 21 monoclonal antibodies before induction of thrombocytopenia by antiplatelet antibody. Four antibodies reacted with the CD24 antigen on erythrocytes. Two antibodies were of the IgM class, and although one IgM antibody caused a minimal degree of anemia (P < .05), neither antibody ameliorated immune thrombocytopenia. One of 2 anti-CD24 antibodies of the IgG class ameliorated immune thrombocytopenia and blocked reticuloendothelial system function at the same doses that protected against thrombocytopenia. Some antibodies reactive with other circulating cell types also protected against immune-mediated thrombocytopenia while no antibody without a distinct target antigen in the mice was protective. Protective monoclonal antibodies significantly prevented thrombocytopenia at down to a 1000-fold lower dose (200 μg/kg) as compared with standard IVIG treatment (2 g/kg). It is concluded that monoclonal IgG with specificity for a circulating cellular target antigen may provide an alternative therapeutic approach to treating immune thrombocytopenia.


Blood ◽  
1985 ◽  
Vol 65 (6) ◽  
pp. 1412-1415 ◽  
Author(s):  
JM Friedman ◽  
RH Aster

Abstract We report a brother and sister, both of whom have porencephaly, hydrocephalus, optic atrophy, severe mental retardation, and spastic quadriplegia. In the younger child, abnormal intracranial structure was demonstrated by sonography at 32 weeks' gestation and was suspected earlier. Both children had transient severe thrombocytopenia as newborns. The mother is healthy and has never had purpura or other bleeding symptoms. However, her serum was found to react strongly with platelets from the father and from both children. The antibody in the mother's serum is platelet-specific but does not appear to be directed against any of the known antigens associated with neonatal alloimmune thrombocytopenic purpura (NATP) in other families, including PlA1, PlE2, or Baka. Although the mother's serum reacts with platelets from all 47 unrelated normal donors tested and from both the mothers and the fathers of 17 other children with suspected NATP, it does not react with her own platelets or with platelets from a patient with Glanzmann's thrombasthenia. These observations suggest that the serum from this woman identifies a previously undescribed high-frequency platelet-specific alloantigen and that sensitization to this determinant caused severe immune thrombocytopenia in both her children. It is likely that this led to intracranial hemorrhage in utero in these cases.


Blood ◽  
2002 ◽  
Vol 100 (6) ◽  
pp. 2087-2093 ◽  
Author(s):  
Ryan J. Hansen ◽  
Joseph P. Balthasar

Abstract Experiments were conducted to investigate the effects of intravenous immunoglobulin (IVIG) in a rat model of immune thrombocytopenia (ITP). Rats were pretreated with 0 to 2 g/kg IVIG and then challenged with an antiplatelet antibody (7E3, 8 mg/kg). IVIG effects on 7E3-induced thrombocytopenia and on 7E3 pharmacokinetics were determined. IVIG pretreatment led to significant changes in the degree and time-course of 7E3-induced thrombocytopenia (P = .031). Nadir percent platelet counts were 121% to 279% greater in animals treated with IVIG (0.4-2 g/kg) than in animals receiving 7E3 alone. IVIG treatment also led to dose-dependent increases in 7E3 clearance (P < .001), with more than 2-fold increases in 7E3 clearance seen following the highest dose of IVIG. In vitro experiments showed that IVIG effects on platelet count are not likely due to anti-idiotypic inhibition of 7E3-platelet binding and that IVIG did not directly bind to 7E3. Consequently, IVIG-7E3 binding cannot explain the increase of 7E3 clearance following IVIG treatment. We propose that the observed increase in 7E3 clearance with IVIG therapy is due to saturation of the FcRn salvage receptor for IgG. The importance of the effect of IVIG on 7E3 clearance to the prevention of thrombocytopenia in these animals is unclear at present; nonetheless, these data provide experimental support for a new mechanism of IVIG action in ITP (ie, IVIG-mediated increases in antiplatelet antibody elimination). This model of ITP will be useful for further investigations of IVIG mechanism of action and for development of new therapies for ITP.


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