Incidence, diagnosis, and outcome of immune-mediated thrombotic thrombocytopenic purpura: A nationwide survey by the Spanish registry of thrombotic thrombocytopenic purpura.

BACKGROUND: Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare disease characterized by the presence of anti-ADAMTS13 autoantibodies. Achieving accurate information on incidence and customary disease management is important to provide appropriate diagnostic and therapeutic resources. The aim of this study was to determine the incidence and outcomes of iTTP in Spain. STUDY DESIGN AND METHODS: A cross-sectional survey was carried out among Spanish hospitals, focused on iTTP patients ≥16 years old attended between 2015 and 2017, and those at follow-up before that interval. Incidence, prevalence, mortality, refractoriness, exacerbations, treatment complications, relapses, and sequelae were estimated. RESULTS: Forty-two hospitals covering roughly 20 million inhabitants answered the survey and reported 203 episodes (138 newly-diagnosed and 65 relapses), of which 193 (95.1%) were treated. Incidence was 2.67 (95% CI 1.90-3.45) patients per million inhabitants per year and prevalence 21.44 (95% CI% 19.10-23.73) patients per million inhabitants. At diagnosis, ADAMTS13 activity and anti-ADAMTS13 autoantibody were measured in 97% and 84.3% of reported episodes, respectively. Fifteen patients (7.4%) died as a direct consequence of iTTP, 6 of them before receiving any iTTP-specific treatment. Thirty-one (16.1%) of the 193 treated episodes were refractory to plasma exchange and corticosteroids, and 51 (26.4%) suffered at least one exacerbation. CONCLUSION: iTTP incidence and prevalence were somewhat higher than those documented in neighboring countries. Together with data on treatments and outcomes, this information will allow us to better estimate what is needed to improve diagnosis and prognosis of iTTP patients in Spain.

Control of Epstein-Barr virus load and lymphoproliferative disease by maintenance of CD8+ T lymphocytes in the T lymphocyte-depleted graft after bone marrow transplantation.

Of 100 bone marrow transplant recipients, 30 (30%) received a CD4(+) lymphocyte-depleted graft (1x10(6) CD8(+) T lymphocytes/kg of body weight). Replication of Epstein-Barr virus (EBV) was observed in 40 patients (40%). The use of a CD4(+) lymphocyte-depleted graft was the only independent risk factor for replication of EBV (relative risk, 11.5; 95% confidence interval, 5.8-22.8; P<.0001). Nevertheless, EBV load in those patients was not higher than in the rest of patients, and the low EBV load prevented the development of lymphoproliferative disease. These results suggest that the presence of CD8(+) T lymphocytes in the bone marrow graft can control EBV load, thereby reducing the risk of developing lymphoproliferative disease.