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Bleeding manifestations in primary immune thrombocytopenia (ITP) range from skin petechiae to life-threatening intracranial hemorrhage (ICH). However, the relation between these various bleeding manifestations and the platelet count in ITP remains poorly characterized. Using a nationwide database of patients with ITP during the years 2005 to 2014 (10 years) in Japan, we analyzed 19 415 adult patients newly diagnosed with ITP, including 222 with ICH. The frequency of skin purpura was 64.8%, and this increased linearly with thrombocytopenia without a specific platelet count threshold. In contrast, mucosal bleeding (epistaxis and gingival bleeding) and organ bleeding (melena, hematuria, and ICH) increased exponentially with thrombocytopenia at a platelet count threshold of 10 to 15 × 109/L. Age showed a much weaker correlation than platelet count with skin and mucosal bleeding. However, the incidence of organ bleeding increased exponentially above 60 years of age. Multivariate analysis showed that the presence of mucosal bleeding was a risk factor for occurrence of melena and hematuria but not for ICH. The frequency of ICH was 1.1% and risk factors for ICH were age ≥60 years (odds ratio [OR], 3.09; 95% confidence interval [CI], 2.13-4.47; P < .001), platelet count <10 × 109/L (OR, 2.96; 95% CI, 2.11-4.15; P < .001), and the presence of hematuria (OR, 1.56; 95% CI, 1.04-2.35; P = .033). The relation between ICH and platelet count varied with age. This large-scale analysis of risk factors for bleeding in ITP has revealed distinct characteristics of skin, mucosal, and organ bleeding in adult patients with newly diagnosed ITP, thus indicating those who are at a high risk of severe organ bleeding., (© 2020 by The American Society of Hematology.)

Measurement of reticulated platelet percentage (RP%) is thought to be a useful marker for differential diagnosis and analysis of platelet kinetics in patients with thrombocytopenic disorders. Two methods are used to detect RP; flow cytometric method and immature platelet fraction (IPF) method using automated hematology analyzers. Although IPF% measured by the automated hematology analyzers is simple and convenient, we already reported that IPF% values were highly fluctuated in stored whole blood sample with EDTA-2K at 4 degrees C day by day. In this study we investigated the stability of IPF% in blood samples obtained from 11 patients with chronic immune thrombocytopenic purpura (ITP) and 19 healthy volunteers using the automated hematology analyzer, XE-5000 (Sysmex) under various storage conditions. EDTA-2K, 3.13% sodium citrate, acid-citrate dextrose solution (ACD), citrate-theophylline-adenosine-dipyridamole solution (CTAD), or sodium fluoride was used as an anticoagulant. When blood samples obtained from healthy subjects were stored at 4 degrees C, IPF% values markedly increased in a time-dependent manner by any anticoagulant examined. On the other hand, there was no significant or only slight difference in IPF% values at room temperature (RT) storage except sodium fluoride. However, in patients with ITP the elevated IPF% values fluctuated widely in EDTA-2K, sodium citrate and ACD-anticoagulated samples even at RT storage. In contrast, IPF% values in CTAD samples stored at RT were highly stable in all patients with ITP up to 4 day storage. These results suggest that the measurement of IPF% by XE-5000 provides quite stable data up to 4 day-storage in ITP patients as well as healthy subjects under CTAD-anticoagulation and RT storage conditions.

Immune thrombocytopenic purpura (ITP) is an acquired hemorrhage condition involving accelerated platelet consumption caused by antiplatelet autoantibodies. Although various therapeutic strategies are used to treat patients with ITP, the standard treatment method is steroid therapy. The most important problem with steroid administration may be a prolonged use tendency in many cases, because there are many refractory chronic patients. To elucidate the effects of glucocorticoid on bone mineral density (BMD) in patients with ITP, we retrospectively evaluated the relationship between BMD and the total dose of glucocorticoid or the mean daily dose given. We observed decreased BMD in 66.7% of the patients with ITP to whom glucocorticoid was given, although normal bone BMD was observed in 28.6% of patients with ITP treated without steroids. The mean level of BMD was markedly decreased in steroid-treated patients compared with nonsteroid-treated patients (P < .01). The relationship between BMD and the total dose of glucocorticoid (P = .023) or the mean daily dose revealed a negative correlation (P = .022). Administration of bisphosphonate revealed a significant increase in bone mass in patients at 6 and 12 months after the start of bisphosphonate treatment, despite the aggravation of thrombocytopenia. In conclusion, glucocorticoid-induced osteoporosis was observed in patients with ITP, similar to situation seen in patients with other diseases. Bisphosphonate may be an effective agent for the prevention and treatment of glucocorticoid-induced osteoporosis in patients with ITP scheduled to receive long-term steroid treatment.

This phase II, multicenter, open-label, sequential-cohort, dose-escalation study was designed to evaluate the safety and efficacy of romiplostim, a novel peptibody that increases platelet production, in Japanese patients with chronic immune thrombocytopenic purpura (ITP). Sequential cohorts of four patients each received romiplostim (1, 3, or 6 microg/kg) subcutaneously on days 1 and 8 of the dose-escalation phase. Patients who achieved platelet responses (doubling of baseline platelet counts to > or =50 x 10(9)/L) continued romiplostim weekly during the treatment-continuation phase. Romiplostim produced dose-dependent increases in mean and peak platelet counts. Five patients received romiplostim during the treatment-continuation phase, with platelet counts > or =50 x 10(9)/L maintained in approximately half of the weekly assessments. Romiplostim was well tolerated. No severe, serious, or life-threatening adverse events were reported. No binding antibodies to romiplostim or thrombopoietin were detected. Romiplostim is safe and well tolerated in Japanese patients with chronic ITP and is effective in producing platelet count increases, consistent with the results from studies in non-Japanese patients. On the basis of these findings, a starting dose of 3 microg/kg was recommended for phase III evaluation of romiplostim in Japanese patients with chronic ITP.

Background: We proposed diagnostic criteria for immune thrombocytopenic purpura (ITP) by modifying the existing guidelines for diagnosis of ITP and by incorporating laboratory tests found useful for predicting its diagnosis, for example erythrocyte count, leukocyte count, anti-GPIIb/IIIa antibody-producing B cells, platelet-associated anti-GPIIb/IIIa antibodies, percentage of reticulated platelets, and plasma thrombopoietin., Objective and Methods: To validate our criteria, we conducted a multi-center prospective study involving 112 patients with thrombocytopenia and a morphologically normal peripheral blood film at the first visit. Each patient underwent a physical examination, routine laboratory tests, and specialized tests for the anti-GPIIb/IIIa antibody response and platelet turnover., Results: Ninety-one patients (81%) satisfied the proposed criteria at first visit. Clinical diagnosis was made by skilled hematologists > 6 months after the first visit; ITP was diagnosed in 88 patients and non-ITP disorders in 24. The proposed criteria had 98% sensitivity, 79% specificity, a 95% positive predictive value, and a 90% negative predictive value. A relatively low specificity appears to be attributed to a few patients who had both ITP and aplastic anemia or myelodysplastic syndrome., Conclusions: Our preliminary diagnostic criteria based on ITP-associated laboratory findings were useful for the differential diagnosis of ITP, but additional evaluations and modifications will be necessary to develop criteria that can be used routinely.

To elucidate the effects of glucocorticoid on bone mineral density in idiopathic thrombocytopenic purpura (ITP) patients, we retrospectively evaluated the relationship between bone mineral density (BMD) and the total dose of glucocorticoid or the mean daily dose given. We found decreased BMD in 66.7% of the patients with ITP to whom glucocorticoid was given, though rather normal bone BMD was observed in 28.6% of ITP patients treated without steroids. The mean level of BMD was markedly decreased in steroid-treated patients compared with steroid non-treated patients (p < 0.01). The relationship between BMD and the total dose of glucocorticoid (p = 0.023) or the mean daily dose revealed a negative correlation (p = 0.022). This study showed that glucocorticoid-induced osteoporosis was observed in patients with ITP, similar to other diseases already reported. When we think of this disease, many cases tend to be followed for a long time, and as the majority of ITP patients is female, we should pay particular attention in the prevention of glucocorticoid-induced osteoporosis.

A retrospective study was performed to determine the prevalence of Helicobacter pylori (H pylori) infection, the effect of H pylori eradication on platelet counts, and the characteristic clinical features of chronic immune or idiopathic thrombocytopenic purpura (ITP) with H pylori infection. H pylori infection was found in 300 patients, a group that was significantly older (P < .005) and had more cases of hyperplastic megakaryocytes in the bone marrow (P = .01) than patients without H pylori infection. H pylori eradication therapy was performed in 207 H pylori-positive ITP cases, and the platelet count response was observed in 63% of the successful eradication group and in 33% of the unsuccessful eradication group (P < .005). In the successful group, the complete remission and partial remission rates were 23% and 42%, respectively, 12 months after eradication. In the majority of responders, the platelet count response occurred 1 month after eradication therapy, and the increased platelet count continued without ITP treatment for more than 12 months. H pylori eradication therapy was effective even in refractory cases, which were unresponsive to splenectomy. In conclusion, H pylori infection was involved in most ITP patients older than 40 years in Japan, and eradication therapy should be the first line of treatment in H pylori-positive ITP patients.

Blockade of the CD40/CD154 signal is a potential immunomodulatory strategy for T-cell-mediated diseases. As a part of a phase 1, multicenter, dose-escalating trial of humanized monoclonal antibody to CD154 (IDEC-131/E6040) in patients with refractory immune thrombocytopenic purpura (ITP), the autoimmune response to glycoprotein IIb/IIIa (GPIIb/IIIa) was evaluated at successive time points. Five patients each were given a single infusion of 1, 2, 5, or 10 mg/kg IDEC-131/E6040 and followed for 3 months. All adverse events were mild, and there were no severe infections or thromboembolic events. No increase in platelet count was observed in patients treated at 1, 2, or 5 mg/kg, but an increase was observed in 3 patients treated at 10 mg/kg. In only the patients treated at 5 or 10 mg/kg, the frequency of B cells producing anti-GPIIb/IIIa antibodies, GPIIb/IIIa-induced T-cell proliferation, and anti-GPIIb/IIIa antibody production by antigen-dependent T-B-cell collaboration were all suppressed in parallel after the treatment, with a slow return to baseline. In contrast, T-cell response to an irrelevant antigen was not affected. These findings suggest that CD40/CD154 blockade therapy is potentially effective for refractory ITP, through selective suppression of autoreactive T and B cells to platelet antigens.

Idiopathic thrombocytopenic purpura(ITP) is autoimmune disorder characterized by production of anti-platelet autoantibodies. The first recommended therapy is an administration of corticosteroid. For the patients refractory to steroid, splenectomy is recommended. In a portion of patients these standard therapies are not effective, therefore, effective new therapies are looked for. In this paper following new therapeutic approaches are presented; 1) eradication of Helicobacter pylori, 2) administration of thrombopoietin, 3) administration of anti-CD40L monoclonal antibodies, 4) administration of anti-CD20 monoclonal antibodies, 5) splenic irradiation. These treatment options are now tried in a small group of refractory patients except for eradication of pylori. We hope these new therapeutics will be introduced in clinical practice in near future.

Platelet activation causes a change in surface expression of several endogenous proteins, such as CD62P, CD63 and CD40L. Therefore, it is possible to analyze the functional in vivo status of the circulating platelet population directly by flow cytometry. In this study we developed the method to be suitable for use in clinical studies. We used EDTA-2K as anticoagulant since the sample anticoagulated with EDTA-2K, sodium citrate or ACD-A showed no difference in the data of activated platelets. We determined whether fixation of sample is necessary. The samples stained before or without fixation showed abnormally high level of activated platelets, indicating that fixation is necessary before staining. It is controversial whether activated platelets circulate in patients with idiopathic thrombocytopenic purpura(ITP). We measured activated platelets in patients with ITP using our optimised method. The percentages of CD62P, CD63 and CD40L positive platelets were significantly high in patients with ITP and 24%, 55% and 36% (respectively) of ITP patients showed elevated level of activated platelets. These data indicate that activated platelets circulate in ITP patients.

Localization of epitopes for platelet-associated (PA) anti-GPIIb-IIIa (alpha(IIb)beta(3)) autoantibodies in chronic immune thrombocytopenic purpura remains elusive. Previous studies suggest that PA antibodies recognize the tertiary structure of intact glycoprotein (GP) IIb-IIIa. To localize their epitopes using antigen-capture enzyme-linked immunosorbent assay (ELISA), the reactivity of 34 PA anti-GPIIb-IIIa antibodies was examined with recombinant GPIIb-IIIa having a defect in ligand-binding sites in either GPIIb or GPIIIa, and no major conformational change was induced: KO variant GPIIb-IIIa was attributed to a 2-amino acid insertion between residues 160 and 161 in the W3 4-1 loop in GPIIb, and CAM variant GPIIb-IIIa was attributed to D119Y in GPIIIa. In one third (11 of 34) of the patients, PA antibodies showed a marked decrease (less than 50%) in reactivity with KO compared with wild-type GPIIb-IIIa. Their reactivity was also impaired against GPIIbD163A-IIIa. In sharp contrast, they reacted normally with CAM GPIIb-IIIa. OP-G2, a ligand-mimetic monoclonal antibody, markedly inhibited their binding to GPIIb-IIIa in patients with impaired binding to KO GPIIb-IIIa, but small GPIIb-IIIa antagonists did not. In addition, a newly developed sensitive ELISA indicated that autoantibodies showing impaired binding to KO are more potent inhibitors for fibrinogen binding. The present data suggest that certain PA anti-GPIIb-IIIa autoantibodies recognize epitopes close to the ligand-binding site in GPIIb, but not in GPIIIa.

We measured reticulated platelets (RPs) and plasma glycocalicin (GC) and thrombopoietin (TPO) levels simultaneously in 107 thrombocytopenic patients to clarify the diagnostic value of these tests for discriminating hyperdestructive from hypoplastic thrombocytopenia. The percentage of RPs and GC index (plasma GC level normalized for the individual platelet count) were markedly elevated in patients with idiopathic thrombocytopenic purpura (ITP) but normal or slightly elevated in patients with aplastic anemia (AA) or chemotherapy-induced thrombocytopenia (ChemoT). For RP percentage for diagnosing hyperdestructive thrombocytopenia the sensitivity and specificity were excellent but were lower for the GC index. Absolute RP counts and plasma GC levels were markedly decreased and plasma TPO levels markedly elevated in patients with AA or ChemoT, but absolute RP counts and plasma GC levels were moderately decreased and plasma TPO levels only slightly elevated in patients with ITP. The sensitivity and specificity of plasma TPO levels for diagnosing hypoplastic thrombocytopenia were excellent. Using the RP percentage and plasma TPO levels in combination improved specificities. Simultaneous measurement of RP percentage and plasma TPO level may help discriminate thrombocytopenia of unknown cause in routine hematologic practice.

In chronic immune thrombocytopenic purpura (ITP), anti-GPIIb-IIIa (alphaIIbbeta3) autoantibodies have been detected in serum and/or platelet-associated IgG (PAIgG) and considered as one of the major causes. We examined whether anti-alphavbeta3 antibodies might be present in ITP cases because of the similarity between alphavbeta3 and GPIIb-IIIa (alphaIIbbeta3). Modified antigen capture ELISA (MACE) using human umbilical vein endothelial cells (HUVEC) showed the presence of serum anti-alphavbeta3 antibodies in 23 of 80 ITP patients (29%). Cross-adsorption studies between platelets and HUVEC demonstrated that most of anti-alphavbeta3 and anti-GPIIb-IIIa antibodies exclusively reacted with alphavbeta3 and GPIIb-IIIa, respectively. Platelet-associated anti-GPIIb-IIIa antibodies did not react with alphavbeta3, either. Interestingly, patients having anti-alphavbeta3 antibodies showed significantly lower platelet counts than negative patients. These results indicate the serum anti-alphavbeta3 antibodies are different ones from the classical anti-GPIIb-IIIa (alphaIIbbeta3) antibodies and would provide a new insight into the pathophysiology of ITP as well as the autoantigenic epitopes on beta3 integrins.

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by thrombocytopenia due to antiplatelet autoantibodies. It has been demonstrated that the platelet glycoprotein (GP) IIb-IIIa and/or GPIb-IX are major target antigens for the autoantibodies in this disorder. Diagnosis of ITP has usually been based on clinical criteria. However, development of reliable immunological techniques enable us to make a diagnosis of "autoimmune thrombocytopenic purpura" in some patients. In this paper, we review the immunological techniques such as immunoblot assay, immunoprecipitation assay, and modified antigen capture ELISA, and discuss the clinical significance of the detected anti-GPIIb-IIIa auto-antibodies.

The circulating thrombopoietin (TPO) level in 43 patients with chronic immune thrombocytopenic purpura (ITP) was examined by an ELISA system. The TPO level (mean +/- SD) in ITP patients was mildly elevated (1.86 +/- 1.17 fmol/ml) compared to that in normal subjects (0.76 +/- 0.21), and was within the normal range in 30% of ITP patients. In contrast, the TPO level in patients with aplastic anaemia was very high, 12.35 +/- 6.42 fmol/ml. There was no correlation between TPO level and platelet count in ITP patients. Splenectomy was performed in two ITP patients, after which platelet counts increased to normal levels and TPO levels showed a transient increase. These data suggest that reactive TPO production against thrombocytopenia in ITP is small when compared to that in aplastic anaemia. Relative endogenous TPO deficiency may play some role in the pathophysiology of thrombocytopenia in ITP patients.

Using a panel of phospholipid(PL) antigens, we have established an enzyme linked immunosorbent assay (ELISA) for measuring both IgG and IgM type anti-phospholipid antibodies (APA) in sera from patients with systemic lupus erythematosus (SLE), idiopathic thrombocytopenic purpura (ITP) and recurrent fetal abortion (RFA). The percentage of anticardiolipin antibody (aCL) positive patients was increased in SLE (73% for IgG, 74% for IgM), ITP (24% for IgG, 8% for IgM) and RFA (20% for IgG, 52% for IgM) as compared with normal controls. The percentage of other APAs in each disease was significantly different from one another, suggesting the existence of disease-specific APA in these autoimmune disorders. We consider that it is important to analyze these APAs for the investigation of pathogenesis of autoimmune disorders.

Platelet-associated and serum anti-glycoprotein (GP) IIb-IIIa autoantibodies were investigated in 57 patients with chronic immune thrombocytopenic purpura (ITP). In modified antigen capture ELISA (MACE) using GPIIb-IIIa-specific-, GPIIb-specific-, and GPIIIa-specific-monoclonal antibody (mAb) for antigen capture, platelet-associated anti-GPIIb-IIIa antibodies were detected in 14 out of 37 patients (38%), and these antibodies could be detected with all 3 mAbs used for antigen capture. In the MACE using EDTA-treated platelets at 37 degrees C, the reactivity of platelet-associated anti-GPIIb-IIIa antibodies in 9 out of 10 patients was markedly reduced in both cases of GPIIb-specific- and GPIIIa-specific-mAb used. Immunoprecipitation experiments further confirmed that the EDTA-treatment abrogated the antigenicity of GPIIb-IIIa for platelet-associated antibodies in 2 patients. Serum anti-GPIIb-IIIa autoantibodies were detected in 23 out of 57 patients (40%). However, only 7 out of 23 serum anti-GPIIb-IIIa antibodies could be detected with all 3 mAbs. The MACE using EDTA-treated platelets further showed that the features of serum anti-GPIIb-IIIa antibodies were different from those of platelet-associated antibodies even in the same patient. Our data demonstrate that the platelet-associated anti-GPIIb-IIIa antibodies mainly recognize the cation-dependent antigenic determinants on GPIIb-IIIa and that serum anti-GPIIb-IIIa antibodies may contain some components which differ in specificity from platelet-associated antibodies.

Male (NZW x BXSB)F1 (W/BF1) mice develop immune thrombocytopenic purpura (ITP), which involves antiplatelet autoantibodies and shortened platelet life span. To determine whether reduction of dietary energy can prevent the development or reverse the progression of ITP, male W/BF1 mice were separated into five experimental groups and either given free access to semipurified diet (designated Group A, n = 50) or consumed 32% less energy from an otherwise comparable diet (Group B6, n = 20), or were initially allowed free access to diet then switched to energy restriction at ages 14, 17 or 22 wk (Groups B14, n = 10; B17, n = 20; B22, n = 20). Thrombocytopenia was prevented by energy restriction in Group B6 mice. Platelet-associated IgG (PAIgG) autoantibody levels and the number of splenic antiplatelet antibody-forming cells were low (P < 0.01) and the survival of injected IgG-coated RBC was extended in energy-restricted Group B6 mice (P < 0.01) compared with mice in Group A. Group A mice became progressively thrombocytopenic, with platelet counts as low as 34 x 10(10)/L. Progression of thrombocytopenia was reversed when energy restriction was initiated in Groups B14, B17 and B22, with platelet counts > or = 88 x 10(10)/L and reduction of PAIgG. Life span was extended among early onset energy-restricted Group B6 and Group B14 mice (P = 0.0001 and P = 0.005) but not among late onset energy-restricted Group B17 and Group B22 mice (P = 0.06 and P = 0.35) compared with Group A mice.(ABSTRACT TRUNCATED AT 250 WORDS)

The clinical significance of high-titer antinuclear antibodies (ANA) and autoantibodies to cellular antigens such as SSA/Ro and nuclear RNP (nRNP) antigens in idiopathic thrombocytopenic purpura (ITP) was examined in a prospective evaluation of 66 adult patients with chronic ITP. ANA were positive in 29 (44%) of 66 patients with chronic ITP. The titers of ANA were high (1:160 or higher) in 14 of 29 ANA-positive patients. Furthermore, 10 of 66 patients had precipitating antibodies to nuclear antigens; seven patients had anti-SSA/Ro antibodies and the other three had anti-nRNP antibodies. None of high-titer ANA- or precipitating antibody-positive patients developed systemic lupus erythematosus (SLE) throughout the follow-up period of 3 years. In addition, we investigated retrospectively precipitating antibodies in stocked sera from 8 patients. These patients had already precipitating antibodies average of 7.7 years before. None of 8 patients developed SLE or Sjogren's syndrome (SS). These data demonstrate that high-titer ANA and antibodies to SSA/Ro or nRNP antigens are often found in patients with ITP, and indicate that the detection of high-titer ANA or the existence of antibodies to SSA/Ro or nRNP antigens by itself is not enough to identify those patients with ITP who are at risk of developing SLE or SS.

Male (NZW x BXSB)F1 (W/BF1) mice develop systemic autoimmunity involving autoantibodies, progressive thrombocytopenia, lupus nephritis, and degenerative coronary vascular disease with myocardial infarction. Platelet-associated IgG (PAIgG) on the platelet surface mediates platelet destruction by the reticuloendothelial system in the autoimmune thrombocytopenic purpura (ATP) of W/BF1 mice. Because the epitopes targeted in ATP by PAIgG have not been identifiable using serum from thrombocytopenic W/BF1 mice, we developed seven hybridomas secreting antiplatelet monoclonal antibodies (MoAbs) using splenocytes of thrombocytopenic W/BF1 mice. Epitopes recognized by three MoAbs were similar to those recognized by PAIgG, because eluted IgG from platelets of thrombocytopenic W/BF1 mice inhibited platelet binding by MoAbs in competitive micro-enzyme-linked immunosorbent assay. Hybridoma cells or purified Ig from the ascites of two clones (2A12 and 6A6), when injected into nude mice produced acute thrombocytopenia, elevated the levels of PAIgG, purpura, and megakaryocytosis. MoAbs of two clones also reacted with single-stranded DNA or double-stranded DNA, and one of these clones (4-13) bound to cardiolipin (CL) but was nonpathogenic in nude mice, suggesting that anti-CL and antiplatelet autoantibodies can be distinct. On immunoblotting analysis, antiplatelet MoAbs frequently bound a 100-Kd platelet protein. These MoAbs contribute to an understanding of the etiopathogenesis of ATP and the several antigens and autoantibodies involved.

This study was designed to investigate the pathogenic relevance of platelet-associated autoantibodies in chronic ITP, since the titer of platelet-associated autoantibodies does not appear to correlate with the severity of the disease. Employing a direct immunoprecipitation procedure, we examined platelets from three ITP patients with platelet-associated autoantibodies against GPIIb-IIIa and an unidentified 56 kD protein before and after splenectomy. In two patients, platelet-associated autoantibodies disappeared after splenectomy, and these two patients attained complete remission. In one patient, however, the amount of platelet-associated autoantibodies did not decrease after splenectomy. Although this patient's platelet count transiently increased to 500 x 10(3)/microliters after splenectomy, it decreased to 55 x 10(3)/microliters within a short time. These findings suggest that platelet-associated autoantibodies play a key role in platelet destruction in chronic ITP.

The clinical significance of antinuclear antibodies (ANA) in patients with chronic idiopathic thrombocytopenic purpura (ITP) was evaluated. Serum samples of 55 patients with ITP without clinical features of systemic lupus erythematosus (SLE) were examined. The average follow-up period was 5.5 years. Positive ANA was found in 23 of the 55 patients. Twelve of these 23 showed a high-titer of ANA. There was no difference in platelet counts between ANA positive patients and negative patients, and there was no correlation between platelet counts and antibody titers. Ten of the 23 positive sera had precipitating antibodies to nuclear antigens; 7 SS-A and 3 RNP antibodies. The platelet counts of the 7 cases with anti-SS-A antibody positive were slightly low compared with those of the anti-SS-A antibody negative patients. None of the 10 patients developed SLE during the average follow-up period of 8.1 years. These results suggest that ITP patients who have a high-titer of ANA or antibody against SS-A do not always develop SLE. It was concluded that ANA with a high titer or precipitin to nuclear antigens, particularly SS-A, dose not predict a high risk of developing SLE in the future.

Effects of splenectomy on platelet kinetics and production of anti-platelet antibodies were studied in male (NZW x BXSB) F1 (W/B F1) mice, which are known as the animal model of immune thrombocytopenic purpura (ITP). Studies on organ localization of radiolabeled platelets revealed that splenic uptake significantly increases in W/B F1 mice in comparison with that of normal controls. W/B F1 mice showed a significant increase in platelet counts and, in contrast with sham-operated controls, high levels of platelet counts were maintained up to 6 weeks after splenectomy. Platelet lifespans (PLSs) did not reach normal levels, although prolonged PLSs were observed. In addition, platelet-associated antibody (PAA) values showed a tendency towards transient decrease, but there was no change in platelet-bindable serum antibodies (PBAs). These findings indicate that the suppression of anti-platelet antibody production is essential to the treatment of ITP; splenectomy may not be effective in treating severely affected ITP patients because, although the spleen is one of the major sites of platelet sequestration and antibody production, reticulo-endothelial systems (RESs) (liver, bone marrow, lymphnodes, etc.) other than the spleen are also responsible for the destruction of platelets. We therefore consider the W/B F1 mouse to be a useful model of human ITP, and believe that it provides valuable information for the development of new therapeutic agents in patients with ITP, especially those who do not respond to splenectomy.

To determine the mechanism by which platelet counts increase after corticosteroid therapy for human immune thrombocytopenic purpura (ITP), we studied the platelet kinetics using prednisolone (PDN)-treated ITP-prone mice, (NZW x BXSB) F1 (W/B F1). An increase in platelet counts was observed in W/B F1 mice (n = 10, mean +/- SD, 1,202 +/- 202 x 10(3)/microL) 4 weeks after treatment with PDN (2 mg/kg/d); no increase occurred in nontreated W/B F1 mice (n = 5,651 +/- 126, P less than .005). Prolonged platelet life-spans (PLSs) were observed in treated W/B F1 mice (1.29 +/- 0.40 days), but not in nontreated controls (0.60 +/- 0.24 days, P less than .01). No increase in platelet production (platelet turnover) was found in PDN-treated W/B F1 mice, but significant decreases in platelet-associated antibodies (PAAs) and platelet-bindable serum antibodies (PBAs) were noted. Studies on organ localization of radiolabeled platelets showed that hepatic uptake significantly decreased in the treated W/B F1 mice, but not in nontreated W/B F1 mice. To elucidate the effect of PDN on the reticulo-endothelial phagocytic activity in W/B F1 mice, we studied in vivo clearance of IgG-sensitized, 51Cr-labeled autologous erythrocytes. W/B F1 mice treated with PDN showed a marked impairment of their ability to clear these cells, although PDN had little effect on the number of splenic or hepatic macrophage Fc gamma receptors. These results and our previous findings of splenectomy suggest that PDN improves platelet counts not only by suppressing systemic reticulo-endothelial phagocytic function but also by reducing antibody production.

Autologous mixed lymphocyte reaction (AMLR)-induced suppressor function was studied in 12 patients with chronic idiopathic thrombocytopenic purpura (ITP). The function was found to be significantly impaired (20 +/- 55%; p less than 0.005) compared with normal subjects (69 +/- 25%). AMLRs in these patients were significantly decreased (p less than 0.05) compared with normal subjects. There was no significant correlation between AMLR-induced suppressor function and platelet counts. Nine patients were studied for AMLR-induced suppressor function before and after splenectomy. The platelet counts increased significantly as a result of splenectomy, but the AMLR-induced suppressor function showed no significant improvement. The results of this study suggest that suppressor dysfunction in ITP may be an immunologic defect irrespective of disease activity. We consider that this abnormality may reflect in vivo failure of the immunoregulatory (feedback) mechanism in ITP.

We investigated 25 pregnancies with ITP. The results were as follows. 1. The platelet counts of the maternal blood just before delivery were not correlated with those of the cord blood. 2. It was suggested that the maternal PAIgG value just before delivery could foretell the onset of neonatal thrombocytopenic purpura. 3. The platelet counts in fetal scalp blood were correlated with those of the cord blood, but falsely lower platelet counts were found in the fetal scalp samples. 4. We saw 5 cases of percutaneous umbilical blood sampling (PUBS) in pregnancies with ITP. PUBS was found to be a useful and safe method. The indications for PUBS and fetal platelet transfusion in pregnancy with ITP are discussed.