Monocyte IL-2Ralpha expression is associated with thrombosis and the JAK2V617F mutation in myeloproliferative neoplasms.

The development of bone marrow fibrosis and thrombosis are main causes of morbidity in essential thrombocythemia (ET). Monocyte activation has been associated to the production of fibrosis-related cytokines and pro-thrombotic factors. The aim of this study was to identify new markers of monocyte activation in Phi-negative myeloproliferative neoplasms and to search for their relationship with clinical features. Forty-five patients comprising 30 ET, eight myelofibrosis and seven polycythemia vera were included. We evaluated the alpha subunit of IL-2 receptor (CD25) on monocytes, basal and LPS-induced IL-1beta release from mononuclear cells, and monocyte TGF-beta mRNA content. Patients who had thrombotic events displayed higher monocyte CD25 levels (6.2%) than those without symptoms (1.3%) and controls (2.6%), p=0.0006. JAK2V617F-positive patients had higher monocyte CD25 expression levels (4.7%), than JAK2V617F-negative (2.6%), p=0.0213. Patients with myeloproliferative neoplasms had similar monocyte CD25 expression than controls, both, in basal conditions and after cell adhesion. IL-1beta release and TGF-beta mRNA levels were normal. In conclusion, increased monocyte CD25 expression is associated with history of thrombosis and is also up-regulated in patients harboring JAK2V617F mutation. The finding of increased CD25 levels together with normal IL-1beta and TGF-beta production reveals a selective monocyte activation profile in myeloproliferative neoplasms.

Effectiveness of anagrelide in the treatment of symptomatic patients with essential thrombocythemia.

We prospectively evaluated the effect of anagrelide on platelet counts and the clinical manifestations of microvascular circulation disturbances in 17 newly diagnosed patients with essential thrombocythemia. Ten patients had symptoms related to thrombocythemia, eight at the time of starting anagrelide treatment. The platelet counts before anagrelide treatment and during maintained remission of essential thrombocythemia by anagrelide were 980 (range, 610-2030) and 378 (range, 212-546) x 10(9)/L, respectively. Spontaneous platelet aggregation was found in 6 patients (35%), which disappeared on remission of essential thrombocythemia in five cases (P = 0.02). Essential thrombocythemia-related microvascular thrombotic and hemorrhagic symptoms disappeared with the normalization of platelet count in all cases during maintained remission of essential thrombocythemia by long term continuous anagrelide treatment with a follow-up period of between 2 and 6 years. However, ET-related symptoms reappeared in three patients, coinciding with increased platelet count up to 600 x 10(9)/L caused by anagrelide dose reduction. We conclude that reduction of increased platelet to normal (< 400 x 10(9)/L) in symptomatic patients with essential thrombocythemia through use of maintained anagrelide treatment is associated with the disappearance of spontaneous platelet aggregation and the complete relief of thrombotic and hemorrhagic manifestations.

[Thromboxane B2 and platelet derived growth factor in essential thrombocythemia treated with anagrelide]. / Tromboxano B2 y factor de crecimiento derivado de las plaquetas en la trombocitemia esencial tratada con anagrelide.

We present herein studies carried out in 17 patients with essential thrombocythemia before treatment with anagrelide and on remission. Ten patients had symptoms related to thrombocythemia, 8 of them at the time of starting treatment. The plasmatic levels of TXB2 and PDGF were measured by ELISA technique. Before treatment, PDGF values corrected for the platelet count were lower than controls, 0.48 ng/10(5) platelets (0.13-1.93) and 0.92 ng/10(5) platelets (0.33-1.16) respectively (p = 0.02), and they were not different from the results obtained during remission. Count-corrected TXB2 levels before treatment were higher than the control group, 1.0 ng/10(5) platelets (0.04-14.4) and 0.25 ng/10(5) platelets (0.13-0.39) respectively (p = 0.04); these values decreased during remission 0.86 ng/10(5) platelets (0.07-9.8) (p = 0.04), although they were still above normal values (p = 0.008). Symptoms disappeared with the normalization of platelet counts in all cases. These results show that patients with essential thrombocythemia during remission have a tendency to normalize the count-corrected TXB2 values.

Tromboxano B2 y factor de crecimiento derivado de las plaquetas en la trombocitemia esencial tratada con anagrelide. / [Thromboxane B2 and platelet derived growth factor in essential thrombocythemia treated with anagrelide]

We present herein studies carried out in 17 patients with essential thrombocythemia before treatment with anagrelide and on remission. Ten patients had symptoms related to thrombocythemia, 8 of them at the time of starting treatment. The plasmatic levels of TXB2 and PDGF were measured by ELISA technique. Before treatment, PDGF values corrected for the platelet count were lower than controls, 0.48 ng/10(5) platelets (0.13-1.93) and 0.92 ng/10(5) platelets (0.33-1.16) respectively (p = 0.02), and they were not different from the results obtained during remission. Count-corrected TXB2 levels before treatment were higher than the control group, 1.0 ng/10(5) platelets (0.04-14.4) and 0.25 ng/10(5) platelets (0.13-0.39) respectively (p = 0.04); these values decreased during remission 0.86 ng/10(5) platelets (0.07-9.8) (p = 0.04), although they were still above normal values (p = 0.008). Symptoms disappeared with the normalization of platelet counts in all cases. These results show that patients with essential thrombocythemia during remission have a tendency to normalize the count-corrected TXB2 values.

[Immunoperoxidase in the studies of immune thrombocytopenias]. / La inmunoperoxidasa en el estudio de las trombocitopenias inmunológicas.

The usefulness of different techniques to measure platelet bound IgG has been reviewed by George. We present here the results obtained with a technique designed to measure membrane bound IgG employing an anti-human IgG labeled with peroxidase and using O-dianisidine-H2O2 to reveal the enzymatic activity. We studied 152 patients with chronic autoimmune thrombocytopenic (ATP) including 120 adults and 32 children (age below 15 years old), diagnosed by exclusion of diseases that may be associated with thrombocytopenic purpura of either immune or nonimmune mechanisms. Besides, 79 patients with thrombocytopenia related to other diseases were also evaluated. The normal values in 215 controls were 188 +/- 4 IgG molec/platelet (mean +/- SE), while in the whole population of chronic ATP the results were 4714 +/- 344, p < 0.001. In pediatric cases the results had a tendency to values higher than in adults. A negative correlation was found between the number of platelets and the amount of bound IgG, r = 0.41 p < 0.001. IgG bound platelets were also increased in treated patients at relapse. The percent of normal IgG bound platelet was 4.5% in patients with a platelet count below 50,000/microliters and 39% in those with normal platelet number. Patients with secondary thrombocytopenia had elevated IgG/platelet while the values were normal in patients with thrombocytopenia of unknown etiology. We conclude that the immunoperoxidase technique is useful to establish the immunologic nature of thrombocytopenia.

La inmunoperoxidasa en el estudio de las trombocitopenias inmunológicas. / [Immunoperoxidase in the studies of immune thrombocytopenias]

The usefulness of different techniques to measure platelet bound IgG has been reviewed by George. We present here the results obtained with a technique designed to measure membrane bound IgG employing an anti-human IgG labeled with peroxidase and using O-dianisidine-H2O2 to reveal the enzymatic activity. We studied 152 patients with chronic autoimmune thrombocytopenic (ATP) including 120 adults and 32 children (age below 15 years old), diagnosed by exclusion of diseases that may be associated with thrombocytopenic purpura of either immune or nonimmune mechanisms. Besides, 79 patients with thrombocytopenia related to other diseases were also evaluated. The normal values in 215 controls were 188 +/- 4 IgG molec/platelet (mean +/- SE), while in the whole population of chronic ATP the results were 4714 +/- 344, p < 0.001. In pediatric cases the results had a tendency to values higher than in adults. A negative correlation was found between the number of platelets and the amount of bound IgG, r = 0.41 p < 0.001. IgG bound platelets were also increased in treated patients at relapse. The percent of normal IgG bound platelet was 4.5

in patients with a platelet count below 50,000/microliters and 39

in those with normal platelet number. Patients with secondary thrombocytopenia had elevated IgG/platelet while the values were normal in patients with thrombocytopenia of unknown etiology. We conclude that the immunoperoxidase technique is useful to establish the immunologic nature of thrombocytopenia.

Inhibitory effect of melatonin on platelet activation induced by collagen and arachidonic acid.

Melatonin, an indolamine synthesized in the pineal gland, is known to have antiprostanoid activity. The inhibition of platelet aggregation induced by melatonin has been proposed to take place through the cyclooxygenase pathway. In the present study, we found that melatonin has a marked inhibitory effect on collagen, arachidonic acid (AA), adenosine diphosphate (ADP), epinephrine, and A23187-induced aggregation in platelet-rich plasma. On the other hand, using metrizamide-filtered platelets resuspended in Tyrode's buffer, melatonin fails to suppress AA-induced platelet aggregation and 14C-5-HT release. Under the same conditions, melatonin inhibits collagen-induced platelet activation; however, the addition of threshold doses of AA (0.3 mM) abrogates this effect. These studies suggest that melatonin also inhibits platelet function at a stage preceding the cyclooxygenase-dependent pathway.