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Dapsone is recommended as a second line therapy in immune thrombocytopenia (ITP), but is underused because of its potential side effects. The medical charts of 42 ITP patients treated with dapsone (100 mg/day) were retrospectively reviewed in order to assess its efficacy and safety in daily clinical practice. The overall response rate was 54.8% (n = 22, with a complete response in 38.1%) with a median time to response of 29 days (24-41 days). Patients with complete response had shorter disease duration whereas no difference was observed between responders and non-responders regarding age, sex or previous treatments received. Importantly, after dapsone withdrawal, a sustained response was observed in 5 patients, representing 12% of the whole cohort. Twenty percent of patients (n = 8) relapsed on therapy after 8.1 (6.5-13.6) months. Side effects occurred in 31% (n = 13) of patients, and required dapsone withdrawal in 22% (n = 9) or dosage reduction in 10% (n = 4) of the cases. Side effects resolved in all but one case. Overall, these data support dapsone as an interesting second line therapy in ITP, with a good safety and efficacy profile at a low cost.

B cells are involved in immune thrombocytopenia (ITP) pathophysiology by producing antiplatelet auto-antibodies. However more than a half of ITP patients do not respond to B cell depletion induced by rituximab (RTX). The persistence of splenic T follicular helper cells (TFH) that we demonstrated to be expanded during ITP and to support B cell differentiation and antiplatelet antibody-production may participate to RTX inefficiency. Whereas it is well established that the survival of TFH depends on B cells in animal models, nothing is known in humans yet. To determine the effect of B cell depletion on human TFH, we quantified B cells and TFH in the spleen and in the blood from ITP patients treated or not with RTX. We showed that B cell depletion led to a dramatic decrease in splenic TFH and in CXCL13 and IL-21, two cytokines predominantly produced by TFH. The absolute count of circulating TFH and serum CXCL13 also decreased after RTX treatment, whatever the therapeutic response. Therefore, we showed that the maintenance of TFH required B cells and that TFH are not involved in the inefficiency of RTX in ITP., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Antiplatelet-antibody-producing B cells play a key role in immune thrombocytopenia (ITP) pathogenesis; however, little is known about T-cell dysregulations that support B-cell differentiation. During the past decade, T follicular helper cells (TFHs) have been characterized as the main T-cell subset within secondary lymphoid organs that promotes B-cell differentiation leading to antibody class-switch recombination and secretion. Herein, we characterized TFHs within the spleen of 8 controls and 13 ITP patients. We show that human splenic TFHs are the main producers of interleukin (IL)-21, express CD40 ligand (CD154), and are located within the germinal center of secondary follicles. Compared with controls, splenic TFH frequency is higher in ITP patients and correlates with germinal center and plasma cell percentages that are also increased. In vitro, IL-21 stimulation combined with an anti-CD40 agonist antibody led to the differentiation of splenic B cells into plasma cells and to the secretion of antiplatelet antibodies in ITP patients. Overall, these results point out the involvement of TFH in ITP pathophysiology and the potential interest of IL-21 and CD40 as therapeutic targets in ITP., (© 2014 by The American Society of Hematology.)

Purpose: Immune thrombocytopenia (ITP) is an auto-immune disease associating a peripheral platelet destruction without increased central production., Methods: Forty patients with chronic ITP were retrospectively analyzed for clinical and biological presentation and response to treatment., Results: Mean age at diagnosis was 54 years. ITP was revealed by hemorrhage in 65 % of the patients. Despite very low platelet count, no life threatening hemorrhage was observed. Platelet associated antibodies were found in 66 %, usually directed against GPIIb/IIIa. Corticosteroids were used as first line treatment, with response in 54 %, and relapse in 86 %. A response was observed in 42.1 % with dapsone, which was well tolerated, a relapse occurring in 37.5 % of the patients. Rituximab (RTX) allowed a response rate of 42.1 %, prolonged in 40 % of the patients. A response was achieved in 42.9 % cases after splenectomy, without any relapse. No factor was identified to predict the response to treatment., Conclusion: ITP is a rare disorder occurring most frequently in middle aged patients. Because of high relapse or no response rates, many treatments should be used. Dapsone offers a good efficacy without major side effects. RTX is well tolerated and allows a good response rate. The use of new agents like thrombopoietin receptor agonist or new therapeutics against B lymphocytes should be defined., (Copyright 2010 Société nationale française de médecine interne (SNFMI). Published by Elsevier SAS. All rights reserved.)