Vaccine-Induced Immune Thrombotic Thrombocytopenia (VITT): Targeting Pathomechanisms with Bruton Tyrosine Kinase Inhibitors.

A series of cases with rare thromboembolic incidents including cerebral sinus vein thrombosis (some of them fatal) and concomitant thrombocytopenia occurring shortly after vaccination with the coronavirus disease 2019 (COVID-19) vaccine AZD1222 (Vaxzevria) have caused significant concern and led to its temporary suspension in many countries. Immediate laboratory efforts in four of these patients have identified a tentative pathomechanism underlying this syndrome termed initially vaccine-induced prothrombotic immune thrombocytopenia (VIPIT) and renamed recently vaccine-induced immune thrombotic thrombocytopenia (VITT). It encompasses the presence of platelet-activating antibodies to platelet factor-4/heparin complexes, possibly emulated by polyanionic constituents of AZD1222, and thus resembles heparin-induced thrombocytopenia (HIT). Because these immune complexes bind and activate platelets via Fcγ receptor IIA (FcγRIIA), high-dose intravenous immunoglobulin G has been suggested for treatment of VITT in addition to non-heparin anticoagulants. Here we propose inhibitors of Bruton tyrosine kinase (Btk) approved for B cell malignancies (e.g., ibrutinib) as another therapeutic option in VITT, as they are expected to pleiotropically target multiple pathways downstream of FcγRIIA-mediated Btk activation, for example, as demonstrated for the effective inhibition of platelet aggregation, dense granule secretion, P-selectin expression and platelet-neutrophil aggregate formation stimulated by FcγRIIA cross-linking. Moreover, C-type lectin-like receptor CLEC-2- and GPIb-mediated platelet activation, the interactions and activation of monocytes and the release of neutrophil extracellular traps, as encountered in HIT, could be attenuated by Btk inhibitors. As a paradigm for emergency repurposing of approved drugs in COVID-19, off-label use of Btk inhibitors in a low-dose range not affecting haemostatic functions could thus be considered a sufficiently safe option to treat VITT.

Indirubin regulates MPL and TNF expression in peripheral blood mononuclear cells from patients with primary immune thrombocytopenia.

Indirubin, a traditional Chinese medicine, is currently used to treat certain autoimmune diseases such as primary immune thrombocytopenia (ITP) in clinics. However, the effects of indirubin on expression of related genes in peripheral blood mononuclear cells (PBMCs) from ITP patients have not been investigated. In the present study, PBMCs were isolated from 19 adult patients with well-characterized active ITP and 20 healthy controls (HCs) and then treated with increasing concentrations of indirubin. The mRNA expression levels of thrombopoietin receptor (MPL), GATA binding protein 3 (GATA3), DNA methyltransferase 3B (DNMT3B), interleukin-6 (IL6), tumor necrosis factor (TNF), and interferon gamma (IFN-γ) were determined by quantitative real-time polymerase chain reaction (PCR). We found that indirubin had no cytotoxic effect on PBMC viability. Significantly lower MPL (p < 0.05) and GATA3 (p < 0.05) expression together with markedly higher IL6 (p < 0.05), TNF (p < 0.0001), and IFN-γ (p < 0.001) mRNA levels were observed in ITP patients compared with HCs. Notably, indirubin significantly enhanced MPL expression and inhibited TNF expression in PBMCs from ITP patients (p < 0.05). In summary, indirubin may play a direct role in thrombopoiesis by activating cellular MPL and normalizing TNF expression to suppress inflammation in ITP. This study may thus improve our understanding of indirubin and provide important information for optimizing therapeutic strategies for ITP patients.

Idiopathic thrombocytopenic purpura: pathogenesis and potential therapeutic approach.

BACKGROUND: This study sought to clarify the pathogenesis of idiopathic thrombocytopenic purpura (ITP) and make preliminary investigations regarding a therapeutic approach. METHODS: Enzyme-linked immunosorbent assay was used to establish and analyze the standard curve for interferon (IFN) γ, interleukin (IL) 4, and IL-17 in order to determine a measurement method for these cytokines. Subsequently, cellular levels of IFN-γ, IL-4, and IL-17 in the peripheral blood of patients in the treatment group (traditional Chinese medicine) was compared with those in the control group (Western-style care). An ITP mice model was also established and treated with different medications. RESULTS: Th1/Th2 cell quantities in ITP patients were significantly higher than in healthy individuals (P<0.05). Furthermore, IL-17 secreted by Th17 cells was significantly higher in ITP patients than healthy individuals (P<0.01). A combination of traditional Chinese medicine and Western-style care yielded the best treatment effect for ITP mice, followed by Western medicine alone and then Chinese medicine alone. CONCLUSIONS: The experimental results suggested that Th17 cells may be more related to the pathogenesis of ITP, and that application of Western-style care supplemented by traditional Chinese medicine may yield a more optimal treatment for ITP.

Effect of Yiqi Tongyang Decoction () on blood T cell subsets in patients with chronic immune thrombocytopenia.

OBJECTIVE: To measure the proportions of blood T cell subsets, Th1, Th2, Th17, Th22, and Treg cells, and other parameters in patients with chronic immune thrombocytopenia (CITP) before and after treatment with Yiqi Tongyang Decoction (, YTD) to explore T cell status of patients with CITP, and to defifine the mechanism of action of YTD. METHODS: The changes in peripheral blood T lymphocyte subsets, and those of Th1, Th2, Th17, Th22, and Treg cells in 30 patients with CITP (22 females and 8 males) were analyzed using multiparametric flflow cytometry before and after treatment with YTD for 6 months, and 26 healthy volunteers (14 males and 12 females) acted as a control. T-box expressed in T-cells (T-bet) and GATA binding protein 3 (GATA-3) mRNA levels in patients and controls were analyzed using real-time reverse transcription-polymerase chain reaction. RESULTS: The proportions of Th1, Th17, Th22, Th1/Th2, and Th17/Treg cells increased in the peripheral blood of patients with CITP compared to those in controls before YTD therapy (P<0.05). Th1 cell numbers and the Th1/Th2 ratio fell in the treated patients with CITP to approximate the values of the control group (P>0.05). Th17 cell numbers and the Th17/Treg ratio also decreased in the treatment group (P<0.05), but not to the levels of the controls. The number of Treg cells in the peripheral blood of patients with CITP before treatment was lower than that in the control group (P<0.05), but increased after YTD treatment P<0.05), but not to the level of controls. T-bet and GATA-3 mRNA levels in peripheral blood were initially higher in patients before treatment than controls (P<0.05), but decreased after YTD therapy (P<0.05). CONCLUSIONS: Imbalances in T lymphocyte levels, particularly those of Th1/Th2 and Th17/Treg cells, play important roles in the pathogenesis of CITP. YTD effificiently regulated the dynamics of Th1/Th2 and Th17/Treg equilibria.

Decreased immunosuppressive actions of 1α, 25-dihydroxyvitamin D3 in patients with immune thrombocytopenia.

Primary immune thrombocytopenia (ITP) is an acquired autoimmune disease. 1α, 25-dihydroxyvitamin D3 [1,25(OH)2D3] and vitamin D receptor (VDR) play important immune-suppressive roles in immune system. It has been reported that serum 1,25(OH)2D3 were lower in ITP patients. In this study, we evaluated local 1,25(OH)2D3 level and VDR mRNA expression further, and determined whether 1,25(OH)2D3/VDR were correlated with T cell dysfunction in ITP patients. We found that 1,25(OH)2D3/VDR levels were decreased in active ITP patients, and 1,25(OH)2D3 had significant anti-inflammatory effects on ITP patients, including both anti-proliferation of peripheral blood mononuclear cells (PBMCs) and reversing the abnormal T cells polarization. 1,25(OH)2D3 inhibited the differentiation of T helper (Th)1 and Tc1 cells but induced the differentiation of Th2, Tc2 and T regulatory (Treg) cells in ITP patients. However, the percentage of Th17 cells were not affected obviously with 1,25(OH)2D3. In addition, 1,25(OH)2D3 also suppressed pro-inflammatory cytokines (INF-γ and IL-17A) but promoted anti-inflammatory cytokine (IL-10) secretion in ITP patients. In conclusion, decreased 1,25(OH)2D3/VDR might participate in the pathogenesis of ITP, and appropriate supplement of 1,25(OH)2D3 may be a promising treatment.

Serum vitamin D levels in children with newly diagnosed and chronic immune thrombocytopenia.

The primary objective of the study was to assess the vitamin D (VD) status of patients suffering from ITP. Children from the case cohort (total 21) were recruited from chronic ITP patients (followed as outpatients) and newly diagnosed ITP (prospective study) patients. VD deficiency (values <75 nmol/L) was detected in 11 patients with newly diagnosed ITP, and seven patients with chronic ITP. Only three patients with newly diagnosed, and none with chronic ITP had normal VD values. Newly diagnosed ITP patients had statistically significantly higher values (P <.044) of VD than the patients with chronic type of ITP. Platelets values did not follow VD level. VD deficiency is very common in children with either newly diagnosed or chronic ITP form. Therefore there is a utility supplementing VD in these patients. To investigate the role of VD as an immune modulating drug for patients with ITP, a prospective randomized placebo-controlled trial needs to be performed.

[Influence of Anticoagulants on Detection of ITP Platelet-Specific Autoantibodies and Relationship of Autoantibody Types with Glucocorticoid Efficacy].

OBJECTIVE: To investigate the influence of divalent cation chelator EDTA and heparin sodium on the detection of ITP platelet-specific autoantibodies by the modified monoclonal antibody immobilization of platelet antigen assay (MAIPA) and to explore the relationship between types of platelet specific autoantibodies and glucocorticoid efficacy. METHODS: The samples were obtained from EDTA- and heparin- anticoagulant ITP patients, respectively, so as to detect the platelet-specific autoantibodies (GPIIb/IIIa and GPIbα) in 140 ITP samples by modified MAIPA, then the differences between these two methods were compared. RESULTS: Out of 140 cases in EDTA group, 55 cases were positive for GPIIb/IIIa, while 76 cases in heparin group were positive for GPIIb/IIIa, 42 cases in both group were repeatable; among them 13 cases were positive in EDTA group and negative in heparin group, while 34 cases were positive in heparin group and negative in EDTA group, there was significant difference between them (x (2) = 9.38, P < 0.05), 62 cases in 140 cases of EDTA group were positive for GPIba, while 51 cases in heparin group were positive for GPIba, 42 cases in both group were repeatabe; among them 20 cases were positive in EDTA group and negative in heparin group, while 9 cases were positive in heparin group and negative in EDTA group, there was no significant difference between them (x (2) = 3.44, P > 0.05). A total of 320 cases received a standard glucocorticoid treatment, out of them 143 cases were positive for GPIbα with effective rate 39.9%, 177 cases were negative for GPIbα with effective rate 79.7%, there was statisticalty significant difference between them (x (2) = 53.115, P < 0.05). CONCLUSION: EDTA anticoagulant (a divalent cation chelator) has a significant influence on detection of ITP platelet-specific autoantibodies (GPIIb/IIIa) by a modified MAIPA method and the GPIbα antibody positive may be one of the important factors that results in un-sensitivity of ITP patients to glucocorticoid treatment.

Profiling of miRNA expression in immune thrombocytopenia patients before and after Qishunbaolier (QSBLE) treatment.

Immune thrombocytopenia (ITP), also known as idiopathic thrombocytopenic purpura, is an autoimmune disease characterized by low platelet count and increased bleeding tendency. Currently, glucocorticoid and splenectomy are the main therapies for ITP but with obvious side effects including tendency of relapse and risk of internal bleeding. In this study, we report the Mongolian medicine Qishunbaolier (QSBLE) can significantly and efficiently increase platelet count with a low recurrent rate and unnoticeable side effect. We profiled the microRNA (miRNA) expression in the blood sample of ITP patients and identified 44 miRNAs that are differentially expressed in ITP patients before and after QSBLE treatment. Out of these 44 miRNAs, 25 are expressed in control subjects and are downregulated in ITP patients, whereas the treatment with QSBLE restores their expressions to the level of control subjects. This result suggests that abnormal expression of these 25 miRNAs might be connected to the pathogenesis of ITP. Interestingly, 14 of those 44 miNRAs are predicted to target at least once on 31 known IPT associated genes, indicating the possible mechanism of QSBLE on ITP therapy.

Combination of recombinant factor VIIa and fibrinogen corrects clot formation in primary immune thrombocytopenia at very low platelet counts.

Haemostatic treatment modalities alternative to platelet transfusion are desirable to control serious acute bleeds in primary immune thrombocytopenia (ITP). This study challenged the hypothesis that recombinant activated factor VII (rFVIIa) combined with fibrinogen concentrate may correct whole blood (WB) clot formation in ITP. Blood from ITP patients (n = 12) was drawn into tubes containing 3·2% citrate and corn trypsin inhibitor 18·3 µg/ml. WB [mean platelet count 22 × 10(9) /l (range 0-42)] was spiked in vitro with buffer, donor platelets (+40 × 10(9) /l), rFVIIa (1 or 4 µg/ml), fibrinogen (1 or 3 mg/ml), or combinations of rFVIIa and fibrinogen. Coagulation profiles were recorded by tissue factor (0·03 pmol/l) activated thromboelastometry. Coagulation in ITP was characterized by a prolonged clotting time (CT, 1490 s (mean)) and a low maximum velocity (MaxVel, 3·4 mm × 100/s) and maximum clot firmness (MCF, 38·2 mm). Fibrinogen showed no haemostatic effect, whereas rFVIIa reduced the CT and increased the MaxVel. The combination of fibrinogen and rFVIIa revealed a significant synergistic effect, improving all parameters (CT 794 s, MaxVel 7·9 mm × 100/s, MCF 50·7 mm) even at very low platelet counts. These data suggest that rFVIIa combined with fibrinogen corrects the coagulopathy of ITP even at very low platelet counts, and may represent an alternative to platelet transfusion.

Immune thrombocytopenia in the elderly: clinical course in 525 patients from a single center in China.

Immune thrombocytopenia (ITP), often diagnosed in the elderly, is a hematologic disorder induced by autoimmune mechanism. In this retrospective study, we evaluated the clinical features, the risk of bleeding, and the response to treatment in 525 elderly ITP patients (age ≥60 years) diagnosed at our center from 1980 to 2009. There were more females at 60-74 years of age (P = 0.044). The median duration of follow-up was 27 months (range 1-253 months). Ten patients developed thrombosis during treatment of ITP. At diagnosis, 461 patients (87.8 %) had signs of bleeding. The risk of severe bleeding was associated with both platelet count (P < 0.001; odds ratio (OR), 0.973) and age (P = 0.025; OR, 1.039). The cutoff points in the platelet count at which bleeding and severe bleeding would begin to appear were 29.5 × 10(9) and 21.5 × 10(9)/L, respectively. Sixteen of 144 patients (11.1 %) who did not receive any treatment achieved remission spontaneously. The total response rate to treatment was 62.4 % (166/266). The median time to remission was 7 days, and combined use of intravenous immunoglobulin and steroids took effect faster than use of steroids alone (P = 0.001). Fifty-two patients (31.3 %) relapsed during follow-up. Of the 27 patients who died during follow-up, seven deaths were directly attributed to ITP. In conclusion, the response rate has been improved since the last 10 years. ITP is also a self-limited disease to some extent in the elderly, but easy to relapse. This review represents the largest collection of elderly ITP patients in China in a single center.

Canadian cost- utility analysis of intravenous immunoglobulin for acute childhood idiopathic thrombocytopenic purpura.

BACKGROUND: Idiopathic thrombocytopenic purpura (ITP) is a hematological disorder and can be classified as acute or chronic. The main goal of treatment for acute childhood ITP is the prevention of potentially fatal bleeding complications, the most serious of which is intracranial hemorrhage (ICH). Treatment options for acute childhood ITP include splenectomy, corticosteroids, and blood products such as intravenous immunoglobulin. OBJECTIVES: The objective was to evaluate, from a Canadian perspective, the cost-effectiveness of intravenous immunoglobulin (IVIG) compared to alternative inpatient treatments for acute childhood idiopathic thrombocytopenic purpura (ITP). METHODS: A Markov model with a lifelong time horizon was used to evaluate the costs and quality-adjusted life years (QALYs) for 5 treatments for children hospitalized for ITP: 1) no treatment; 2) IVIG; 3) Anti-D; 4) prednisone; and 5) methylprednisolone. The model predicted the probability of intracranial hemorrhage for each treatment strategy based on the time children spent with platelet counts <20,000µL. The time patients spent with platelet counts <20,000µL with each treatment was estimated by pooling data from published randomized clinical trials. In the basecase analysis, the cohort was assumed to weigh 20kg. Cost and utility model variables were based upon various literature sources. Parameter uncertainty was assessed using probabilistic sensitivity analysis. RESULTS: The treatment strategies that comprised the efficiency frontier were prednisone, Anti-D and IVIG. The incremental cost per QALY was $53,333 moving from prednisone to Anti-D and $53,846 moving from Anti-D to IVIG. Results were sensitive to patient weight. If patient weight is 10kg, IVIG dominates all other strategies and if weight is increased to 30kg, the cost per QALY of IVIG is $163,708. CONCLUSION: Based on common willingness to pay thresholds, IVIG might be considered a cost effective treatment for acute childhood ITP. Cost effectiveness is highly dependent on patient weight.

[Regulation of erythropoiesis in patients with suppressed hematopoiesis during mountain climatic treatment].

AIM: to estimate the regulation of erythropoiesis and the coagulation system in patients with suppressed hematopoiesis in a mountain hospital (3200 m above sea level). SUBJECTS AND METHODS: The investigation included 12 patients with aplastic anemia (AA) and 10 with idiopathic thrombocytopenic purpura (ITP). Blood was received at a Bishkek hospital, then on days 20 and 40 of stay in the mountains. The authors studied erythropoietin (EPO) by enzyme immunoassay (Protein Contour kit, Russia), serum ferritin (SF) by immunoradioassay (Immunotech kit, Czech Republic), hypoxia-inducible factor-1alpha (HIF-1alpha), homocysteine (HC), hepcidin, endothelin (ET), and thrombomodulin (TM) by sandwich enzyme immunoassay, by applying monospecific antisera and monoclonal antibodies against relevant antigens (IDG Int Inc, USA). RESULTS: On staying in the mountains, there was a gradual increase in the content of hemoglobin in patients with AA and ITP. On day 40, in keeping with higher hemoglobin (Hb) levels, both groups showed a decrease in HIF-1alpha concentrations to the normal values (from 8.2 to 4.5 pg/ml). Due to the anemic syndrome, baseline EPO was increased by 5-7 times in the patients from both groups. On days 20-40, the content of EPO showed a 1.3-2.5-fold increase. In AA, HC was almost 3 times greater than the normal values; in ITP, it was 1.5-fold increased. On day 20 and during the patients'stay in the mountains, the level of HC remained in the normal range in both groups. CONCLUSION: Hypoxic hypoxia positively affects a number of hematological parameters, by normalizing erythropoiesis (Hb, EPO, and HIF-1alpha), iron metabolism (SF), and the coagulation system (HC, ET, and TM).

Treatment of 37 patients with refractory idiopathic thrombocytopenic purpura by shengxueling.

OBJECTIVE: To explore the clinical effect and possible mechanism of Shengxueling (SXL), a Chinese medical preparation mainly consisting of ginseng saponins, in treating refractory idiopathic thrombocytopenic purpura (ITP). METHODS: The selected 69 patients with ITP were randomly assigned to two groups, the 37 patients in the treated group were treated orally by SXL with the dose for adult as 60 mg twice a day for two weeks. Then when no marked rise of platelet count after that, the dose would be doubled and administered for another two weeks. Then the dose could be gradually reduced to the initiative level in patients who responded to the treatment, and if they did not, the treatment was regarded as ineffective and be terminated. The 32 patients in the control group were treated with ampeptide elemente instead of SXL, 0.4 g each time three times a day in the first two weeks, and, if that was ineffective, 0.2 g would be added each time and 1.8 g would be administered a day for two more weeks. Four weeks' treatment was regarded as one therapeutic course for both groups and the observation lasted for two successive courses in patients showing positive reslonse. RESULTS: In the 37 patients in the treated group, markedly effective was obtained in 7 (19.0%), favorably effective in 15 (40.5%), improved in 5 (13.5%) and ineffective in 10 (27.0%), the total effective rate being 59.5%. The corresponding number in the 32 patients in the control group was 4 (12.5%), 6 (18.8%), 3 (9.4%), 19 (59.4%) and 31.3% respectively. Comparison showed the difference in therapeutic efficacy between the two groups was significant (P<0.05). CONCLUSION: SXL is a safe and effective preparation for treatment of ITP, showing an immediate effect which is obviously superior to that of ampeptide elemente with less adverse effect.

Características clínicas del púrpura trombocitopénico inmune: revisión de 52 casos / Clinical characteristics of inmune thrombocytopenic purpura

Introducción: El Púrpura Trombocitopénico Inmune (PTI) suele ser autolimitado pero 10-20 por ciento persisten a los 6 meses, es decir de evolución crónica. Su tratamiento es controvertido y existen pocos datos nacionales. Objetivo: Conocer algunas características clínicas y de laboratorio del PTI, su relación con evolución crónica y el manejo actual. Método: Estudio retrospectivo de los 52 pacientes con PTI evaluados en Hospital Luis Calvo Mackenna, entre marzo 1998 y febrero 2003. Se consignó: sexo, edad, manifestaciones clínicas, conducta terapéutica y recuento plaquetario (RP) al diagnóstico, 15-60 días y 6 meses. Se aplicaron Test de Fisher y Odd Ratio. Resultados: Mediana de edad: 4,4 años (0,7 a 16,1), el RP fue < - 20 000 x mm3 en 37/52. No hubo hemorragia del sistema nervioso central. Se manejó con observación clínica 34/52, corticoides 17/52 e inmunoglobulinas endovenosas con corticoides 1/52. Completaron control (6 meses) 48/52 pacientes. Presentaron curso crónico 11/48, asociado a RP 15 días < - 20 000 x mm3 (p = 0,01) OR = 9 (IC95 por ciento: 1,26-80,16) y RP a los 60 días < - 50 000 x mm3 (p = 0,0000003) OR= 124 (IC95 por ciento: 7,77 - 4951,52). Conclusiones: La mayoría de los pacientes requirieron sólo observación clínica. Presentaron evolución crónica 23 por ciento siendo factores de riesgo RP a los 15 días £ 20 000 x mm3 y RP a los 60 días £ 50 000 x mm3.

Clinical study on the effect of Shengxueling on idiopathic thrombocytopenic purpura.

OBJECTIVE: To observe the clinical effect of Shengxueling (SXL) on idiopathic thrombocytopenic purpura (ITP), and study the possible mechanism. METHODS: Eighty-six cases of ITP were randomly divided into two groups. The SXL group, 56 patients treated with SXL, a traditinal Chinese medicine and 30 patients administered with prednisone were taken as control. Each group took drugs for 3 months and was under follow-up observation. RESULTS: In the SXL group, the total effective rate was 85.71%, similar to prednisone 83.33% (P > 0.05) for 3 months, but the total effective rate of SXL (91.07%) were obviously better than that of the control group (53.33%) (P < 0.01) for 6 months and had no obvious adverse reaction. The patients bleeding was alleviated or stopped, the general condition was improved. At the same time, blood platelet count (PLT) was increased, platelet associated immunoglobulin (PAIg) and interleukin-4 (IL-4) were markedly dropped, the level of natural killers cells activity (NKa) increased, the rate of T lymphocyte subsets gradually returned to normal level. Megakaryocyte tended to maturation on bone marrow smear after treatment. All differences above were statistically significant. CONCLUSION: SXL is an effective and safe medicine for ITP. Its mechanism could regulate cytoimmune, inhibit platelet antibody to reduce the destruction of platelet, increase the number of platelet, promote the division and maturation of megakaryocyte, facilitate the production and release of platelet, lower the fragility of capillary, prevent and cure hemorrhagic tendency.

[Treatment of chronic refractory idiopathic thrombocytopenic purpura in children with multiglycosidorum Tripterygii and prednisone].

In order to determine the curative effect of multiglycosidorum Tripterygii and prednisone for treatment of children with chronic refractory idiopathic thrombocytopenic purpura (ITP), a total of 28 patients had been treated with multiglycosidorum Tripterygii and prednisone. Multiglycosidorum Tripterygii was given at a dose of 1 mg/kg body weight per day and the prednisone was given at a dose of 0.5 mg/kg body weight per day for two consecutive months. Bone marrow examination and blood platelet associated immunoglobin G (PAIgG) measurement were performed during the treatment. The results showed that in 21 patients acquired effectiveness, of whom, according the common criteria, 9 patients achieved curative effective, 7 achieved significant effectiveness and 5 effective. 7 patients did not achieve effectiveness. There were no serious side effects associated with therapy. The number of proplatelets on bone marrow smears was increased and the titers of IgG to platelet were restored to normal range in patients achieving remission. In conclusion, combination of multiglycosidorum triptergii with prednisone is effective and safe for treatment of chronic refractory idiopathic thrombocytopenic purpura in children.

Melatonin for refractory idiopathic thrombocytopenic purpura: a report of 3 cases.

In addition to its well-known influence on circadian rhythms, melatonin has been described as being able to increase the number of platelets in circulating blood. This provided the rationale to evaluate melatonin for toxicity and efficacy in three patients with idiopathic thrombocytopenic purpura (ITP) refractory to initial treatment with corticosteroids or splenectomy (refractory ITP). Patients received melatonin for 1 month. The therapy was continued for 2 additional months in patients with stable or responding disease. After 3 months, the stable or responding patients continued the therapy for 3 months and more. All patients had a partial response after 1 month. Continuing with the treatment, none of the three patients had disease progression (average follow-up time of 31 months; range: 23-46 months). Toxicity was lacking, with the only side effect being drowsiness. Our experience suggests that melatonin may be safe and effective in patients with refractory ITP.

Development of a non-human primate sub-clinical model of heparin-induced thrombocytopenia: platelet responses to human anti-heparin-platelet factor 4 antibodies.

The purpose of this study was to characterize the responses of human and non-human primate (Macaca mulatta) platelets to anti-heparin-platelet factor 4 (AHPF4) antibodies. Due to the variations observed in the functionality and immunoglobulin isotypes in patients with heparin-induced thrombocytopenia (HIT), we used highly characterized human AHPF4 antibodies to study platelet activation responses. Using ELISA and 14C-serotonin release assay (SRA) systems, three patients' plasmapheresis fluid with similar responses to these assays were pooled. This pool was then used to study the platelet activation responses of human and primate platelets in the HIT platelet aggregation assay, a flow cytometry assay, and a variation of the aggregation assay in which glycoprotein IIb/IIIa inhibitors were supplemented. In the plasmapheresis fluid from three patients, the most significant AHPF4 immunoglobulin isotype present (based on optical density readings) was IgG, with less IgM (p < 0.001) and IgA (p < 0.001). The SRA yielded equivalent platelet activation results in all three patients. Using this pool in the platelet aggregation assay, without any heparin present, there was less percent aggregation (p < 0.001) with human platelets (11.8 +/- 2.35, n = 5) compared to the primate platelets (54.3 +/- 10.2, n = 9). In presence of 0.4 U/ml heparin, both platelet types had similar percent aggregations (p > 0.05). Three glycoprotein IIb/IIIa receptor inhibitors were used to evaluate the similarities in platelet activation. Eptifibatide was found to be a strong inhibitor of both species' platelet types at concentrations greater than 0.01 microg/ml. This was not the case with tirofiban which inhibited both human and monkey platelets at concentrations greater than 0.025 microg/ml. Abciximab inhibited aggregation at concentrations greater than 6.25 microg/ml. These data indicate that phylogenetic similarities in platelets of humans and primates may be used to further characterize the pathophysiology of HIT syndrome.