Sickle cell disease results from a homozygous missense mutation in the β-globin gene that causes polymerization of hemoglobin S. Gene therapy for patients with this disorder is complicated by the complex cellular abnormalities and challenges in achieving effective, persistent inhibition of polymerization of hemoglobin S. We describe our first patient treated with lentiviral vector–mediated addition of an antisickling β-globin gene into autologous hematopoietic stem cells. Adverse events were consistent with busulfan conditioning. Fifteen months after treatment, the level of therapeutic antisickling β-globin remained high (approximately 50% of β-like–globin chains) without recurrence of sickle crises and with correction of the biologic hallmarks of the disease. (Funded by Bluebird Bio and others; HGB-205 ClinicalTrials.gov number, NCT02151526.)

Objective. Evidence indicates that tumour necrosis factor (TNF) is a major agent in the pathogenesis of vasculitis. We studied the short‐term effect of anti‐TNF‐α antibody in systemic vasculitis patients refractory to steroids and immunosuppressive agents. Methods. Ten patients refractory to corticosteroids and at least one immunosuppressant and who had persistently active disease or a new flare were included. Seven had Wegener's granulomatosis, two had rheumatoid arthritis‐associated vasculitis and one had cryoglobulinaemia with mean duration of 9.1, 21.5 and 17 yr. They received infliximab (5 mg/kg) on days 1, 14, 42 and then every 8 weeks. Immunosuppressants were stopped between days 0 and 42 for eight patients, while the steroid dose was maintained or lowered. The treatment response was evaluated clinically with the Birmingham Vasculitis Activity Score 2000 (BVAS). Results. Complete or partial remission was observed in all patients. The mean BVAS at entry was 9.1 (range 4–15) and had declined to 1.9 (range 0–4) by day 42 and 1.3 (range 0–4) at 6 months; BVAS of 0 was recorded for four patients on day 42 and for five at 6 months. The only adverse effect was cutaneous eruption in two patients. Conclusion. Anti‐TNF‐α successfully induced prompt symptomatic responses in patients with systemic vasculitis not responding to conventional treatment. Infliximab was well tolerated during the short‐term follow‐up.

Delayed hemolytic transfusion reaction (DHTR) is one of the most feared complications of sickle‐cell disease (SCD). We retrospectively analyzed the clinical and biological features, treatments and outcomes of 99 DHTRs occurring in 69 referral center patients over 12 years. The first clinical signs appeared a median of 9.4 [IQR, 3–22] days after the triggering transfusion (TT). The most frequent DHTR‐related clinical manifestation was dark urine/hemoglobinuria (94%). Most patients (89%) had a painful vaso‐occlusive crisis and 50% developed a secondary acute chest syndrome (ACS). The median [IQR] hemoglobin‐concentration nadir was 5.5 [4.5–6.3] g/dL and LDH peak was 1335 [798–2086] IU/L. Overall mortality was 6%. None of the patients had been receiving chronic transfusions. Among these DHTRs, 61% were developed in previously immunized patients, 28% in patients with prior DHTR. Among Abs detected after the TT in 62% of the episodes, half are classically considered potentially harmful. No association could be established between clinical severity and immunohematological profile and/or the type and specificity of Abs detected after the TT. Management consisted of supportive care alone (53%) or with adjunctive measures (47%), including recombinant erythropoietin and sometimes rituximab and/or immunosuppressants. Additional transfusions were either ineffective or worsened hemolysis. In some cases, severe intravascular hemolysis can be likely responsible for the vascular reaction and high rates of ACS, pulmonary hypertension and (multi)organ failure. In conclusion, clinicians and patients must recognize early DHTR signs to avoid additional transfusions. For patients with a history of RBC immunization or DHTR, transfusion indications should be restricted. Am. J. Hematol. 91:989–994, 2016.

Dense, dehydrated red blood cells (DRBCs) are a characteristic feature of sickle-cell disease (SCD). DRBCs play a role in the pathophysiology of SCD acute and chronic organ damage because of heightened tendency to undergo polymerization and sickling because of their higher hemoglobin S concentration. Relations between red cell density (assessed with phthalate density-distribution profile method) and several hematologic, biochemical, genetic parameters, and clinical manifestations were studied in a large cohort of homozygous patients. The percentage of DRBCs was significantly higher in patients who experienced skin ulcers, priapism, or renal dysfunction. Presence of α-thalassemia deletions was associated with fewer DRBCs. A multivariable analysis model showed DRBCs to be positively associated with hemolytic parameters such as lactate dehydrogenase and bilirubin and negatively with fetal hemoglobin. The percentage of DRBCs decreased by 34% at 6 months of hydroxycarbamide (xydroxyurea) therapy. Thus, DRBCs are associated with specific clinical manifestations and biologic markers and may be a useful addition to the biologic and clinical evaluation of patients with SCD, because they can easily be measured in a hematocrit tube.

Lunatic Fringe (Lfng) enhances Notch1 activation by Delta-like 4 (DL4) to promote Notch1-dependent T-lineage commitment of thymus-seeding progenitors. Subsequently, Notch1 and T-cell receptor-β (TCRβ)–containing pre-TCR complexes signal CD4/CD8 double-negative 3 (DN3) committed T-cell progenitors to survive, proliferate, and differentiate into CD4/CD8 double-positive (DP) αβ T-cell precursors. Few DP thymocytes develop without Notch1 or pre-TCR signals, whereas ectopic Notch1 activation causes T-cell leukemia. However, mechanisms of a Notch-pre-TCR collaboration during this “β-selection” process are poorly understood. We genetically manipulated Lfng to attenuate or enhance Notch1 activation in DN3 thymocytes without inducing leukemogenesis. We show that Lfng temporally sustains DL-induced Notch1 signaling to prolong proliferative self-renewal of pre-DP thymocytes. Pre-TCR signaling greatly augmented Notch trophic functions to promote robust proliferation of pre-DP progenitors. In contrast, in the absence of DL/Notch signaling, pre-TCR-expressing progenitors rapidly atrophied and differentiated into DP thymocytes. Thus, Lfng prolongs Notch1 signaling to promote self-renewal more than differentiation during the early stages of β-selection. Our data provide novel insights into the Notch-pre-TCR collaboration, and suggest that decreasing Lfng expression during the DN3-DP transition minimizes the potent leukemogenic potential of Notch1 signaling.