Quelques représentations à propos des vaccinations et des transplantations

Les pratiques de vaccination, de prévention des épidémies, de greffes et de transplantations, ainsi que les règlements et les institutions qui les concrétisent, constituent une source de représentations concernant l'immunologie qu'un enseignement se doit d'analyser. Sur le trajet de l'assimilation d'un savoir (concepts, techniques, méthodes), ces représentations seront source d'intérêt pédagogique, aides ou obstacles selon les situations. L'analyse concerne ici des élèves de 14 à 18 ans de l'enseignement secondair

Splenectomy and/or cyclophosphamide as salvage therapies in thrombotic thrombocytopenic purpura: the French TMA Reference Center experience: SALVAGE THERAPIES IN SEVERE TTP

BACKGROUND: The objective was to assess the efficacy and safety of splenectomy and cyclophosphamide as salvage therapies in severe thrombotic thrombocytopenic purpura (TTP).STUDY DESIGN AND METHODS: During a 10-year period, patients who did not improve with plasma exchanges, steroids, vincristine, and/or rituximab were considered for splenectomy or cyclophosphamide. Patients with a documented severe (<10% of normal value) acquired ADAMTS13 deficiency are reported here. RESULTS: Eighteen patients with a severe acquired ADAMTS13 deficiency required a salvage therapy. Thirteen patients had a splenectomy 19 (interquartile range [IQR], 10-51) days after TTP diagnosis. One patient died the day after splenectomy. The remaining patients improved platelets (PLTs) until Day 6, along with a rapid and major lactate dehydrogenase improvement. Six patients, however, subsequently experienced a transient worsening. Durable PLT count recovery in survivors was observed within 13 (IQR, 11.5-25.5) days. Postoperative complications included thromboembolic events (two cases) and infections (five cases). Five patients received pulses of cyclophosphamide 12 (IQR, 12-15) days after TTP diagnosis. All patients recovered PLTs 10 (IQR, 9-24) days after the first pulse and two experienced a transient worsening. Three patients experienced infections. Three relapses occurred 5 months, 2.5 years, and 4.5 years after splenectomy and one relapse occurred 3.5 years after cyclophosphamide. After a 2.5 (IQR, 0.75-6.2)-year follow-up, the overall survival was 94%. CONCLUSION: Cyclophosphamide and splenectomy provide comparable high remission rates in severe TTP with acceptable side effects and should be considered in the more severe patients who do not improve with other therapies

Accuracy Assessment of the ESA CCI 20M Land Cover Map: Kenya, Gabon, Ivory Coast and South Africa

This working paper presents the overall and spatial accuracy assessment of the European Space Agency (ESA) 20 m prototype land cover map for Africa for four countries: Kenya, Gabon, Ivory Coast and South Africa. This accuracy assessment was undertaken as part of the ESA-funded CrowdVal project. The results varied from 44% (for South Africa) to 91% (for Gabon). In the case of Kenya (56% overall accuracy) and South Africa, these values are largely caused by the confusion between grassland and shrubland. However, if a weighted confusion matrix is used, which diminishes the importance of the confusion between grassland and shrubs, the overall accuracy for Kenya increases to 79% and for South Africa, 75%. The overall accuracy for Ivory Coast (47%) is a result of a highly fragmented land cover, which makes it a difficult country to map with remote sensing. The exception was Gabon with a high overall accuracy of 91%, but this can be explained by the high amount of tree cover across the country, which is a relatively easy class to map

Immune-checkpoint expression in Epstein-Barr virus positive and negative plasmablastic lymphoma: a clinical and pathological study in 82 patients

International audiencePlasmablastic lymphoma is a rare and aggressive diffuse large B-cell lymphoma commonly associated with Epstein-Barr virus co-infection that most often occurs in the context of human immunodeficiency virus infection. Therefore, its immune escape strategy may involve the upregulation of immune-checkpoint proteins allowing the tumor immune evasion. However, the expression of these molecules was poorly studied in this lymphoma. We have investigated 82 plasmablastic lymphoma cases of whom half were Epstein-Barr virus positive. Although they harbored similar pathological features, Epstein-Barr virus positive plasmablastic lymphomas showed a significant increase in MYC gene rearrangement and had a better 2-year event-free survival than Epstein-Barr virus negative cases (P=0.049). Immunostains for programmed cell death-1, programmed cell death-ligand 1, indole 2,3-dioxygenase and dendritic cell specific C-type lectin showed a high or moderate expression by the microenvironment cells in 60%–72% of cases, whereas CD163 was expressed in almost all cases. Tumor cells also expressed programmed cell death-1 and its ligand in 22.5% and 5% of cases, respectively. Both Epstein-Barr virus positive and negative plasmablastic lymphomas exhibited a high immune-checkpoint score showing that it involves several pathways of immune escape. However, Epstein-Barr virus positive lymphomas exhibited a higher expression of programmed cell death-1 and its ligand in both malignant cells and microenvironment as compared to Epstein-Barr virus negative cases. In conclusion, plasmablastic lymphoma expresses immune-checkpoint proteins through both malignant cells and the tumor microenvironment. The expression of programmed cell death-1 and its ligand constitutes a strong rationale for testing monoclonal antibodies in this often chemoresistant disease

Prognostic value of inhibitory anti-ADAMTS13 antibodies in adult-acquired thrombotic thrombocytopenic purpura.

International audienceIn order to assess the prognostic value of inhibitory anti-ADAMTS13 antibodies in thrombotic thrombocytopenic purpura (TTP), we performed a multicentre prospective study of 33 adult patients with idiopathic acquired TTP. Patients were treated with high-dose plasma infusion and therapeutic plasma exchange. Patients without (group 1, n = 12) and with (group 2, n = 21) detectable inhibitory anti-ADAMTS13 antibodies were compared for clinical presentation, treatment and outcome. Both groups were comparable for clinical presentation. All patients in group 1 achieved a sustained complete remission within a median of 7 d [95% confidence interval (CI), 4-18], which required a median plasma volume of 235 ml/kg (range, 131-1251). In group 2, 17 patients achieved a durable complete remission within a median of 23 d (95% CI, 11-32) (P = 0.001). Median plasma volume was 718 ml/kg (range, 219-3107) (P = 0.02). In group 2, there was a trend for more episodes of flare-up than in group 1 (13 vs. 3, respectively, P = 0.07). Four patients, all from group 2, died (P = not significant). The relapse rate was comparable between both groups. We suggest that TTP with detectable inhibitory anti-ADAMTS13 antibodies displays a worse prognosis, relative to a delayed platelet count recovery, a higher plasma volume requirement to achieve complete remission, and a trend for more frequent episodes of flare-up