Key Points• Initial imatinib-based therapy of Ph1 adult ALL is associated with lower early mortality and higher CR rate.• In adults with Ph1 ALL, allogeneic SCT in first CR prolongs relapse-free survival and OS.In this study, we randomly compared high doses of the tyrosine kinase inhibitor imatinib combined with reduced-intensity chemotherapy (arm A) to standard imatinib/hyperCVAD (cyclophosphamide/vincristine/doxorubicin/dexamethasone) therapy (arm B) in 268 adults (median age, 47 years) with Philadelphia chromosome-positive (Ph1) acute lymphoblastic leukemia (ALL). The primary objective was the major molecular response (MMolR) rate after cycle 2, patients being then eligible for allogeneic stem cell transplantation (SCT) if they had a donor, or autologous SCT if in MMolR and no donor. With fewer induction deaths, the complete remission (CR) rate was higher in arm A than in arm B (98% vs 91%; P 5 .006), whereas the MMolR rate was similar in both arms (66% vs 64%). With a median follow-up of 4.8 years, 5-year event-free survival and overall survival (OS) rates were estimated at 37.1% and 45.6%, respectively, without difference between the arms. Allogeneic transplantation was associated with a significant benefit in relapse-free survival (hazard ratio [HR], 0.69; P 5 .036) and OS (HR, 0.64; P 5 .02), with initial white blood cell count being the only factor significantly interacting with this SCT effect. In patients achieving MMolR, outcome was similar after autologous and allogeneic transplantation. This study validates an induction regimen combining reduced-intensity chemotherapy and imatinib in Ph1 ALL adult patients and suggests that SCT in first CR is still a good option for Ph1 ALL adult patients. This trial was registered at www.clinicaltrials.gov as #NCT00327678. (Blood. 2015;125(24):3711-3719)

Selectins and their ligand P-selectin glycoprotein ligand-1 (PSGL-1) mediate leukocyte rolling along inflamed vessels. Cell rolling is modulated by selectin interactions with their ligands and by topographic requirements including L-selectin and PSGL-1 clustering on tips of leukocyte microvilli. Lipid rafts are cell membrane microdomains reported to function as signaling platforms. Here, we show that disruption of leukocyte lipid rafts with cholesterol chelating agents depleted raft-associated PSGL-1 and Lselectin and strongly reduced L-, P-, and E-selectin-dependent rolling. Cholesterol repletion reversed inhibition of cell rolling. Importantly, leukocyte rolling on Pselectin induced the recruitment of spleen tyrosine kinase (Syk), a tyrosine kinase associated to lipid raft PSGL-1. Furthermore, inhibition of Syk activity or expression, with pharmacologic inhibitors or by RNA interference, strongly reduced leukocyte rolling on P-selectin, but not on E-selectin or PSGL-1. These observations identify novel regulatory mechanisms of leukocyte rolling on selectins with a strong dependency on lipid raft integrity and Syk activity. IntroductionSelectins initiate leukocyte tethering and rolling along the inflamed vascular wall. 1-3 L-selectin is expressed by most leukocytes, whereas P-and E-selectin expression is induced on activated platelets and/or endothelial cells. In early inflammation, leukocyte rolling depends mainly on P-selectin interactions with P-selectin glycoprotein ligand-1 (PSGL-1). 4,5 PGSL-1 is also a major ligand for L-selectin and mediates secondary interactions between circulating and adherent leukocytes or leukocyte fragments. [6][7][8][9] In addition, PSGL-1 cooperates with other adhesion receptors to support leukocyte rolling on E-selectin. [10][11][12][13] Several observations indicate that PSGL-1 is a signaling molecule. Engagement of leukocyte PSGL-1 induces Ras and MAPK activation as well as interleukin-8, tissue factor, or colonystimulating factor-1 secretion. 14-17 PSGL-1 interactions with Pselectin promote the binding of PSGL-1 cytoplasmic domain to actin-binding proteins ezrin and moesin. [18][19][20] Moesin serves as an adaptor between PSGL-1 and Syk. 21 PSGL-1 engagement induces Syk tyrosine phosphorylation and generates intracellular signals leading to expression of early-immediate activation genes such as c-fos. 21 Whether Syk is involved in regulating leukocyte rolling has not yet been examined.PSGL-1 and L-selectin are detectable in membrane lipid rafts of human cell lines. 22,23 The lipid raft model proposes that these cholesterol-and glycosphingolipid-rich microdomains function as key cellular membrane signaling platforms. 24,25 We therefore examined whether lipid rafts were required for PSGL-1 and L-selectin function. Moreover, as Syk was shown to colocalize in lipid rafts with tyrosine phosphatase CD45 upon B-lymphocyte activation via the B-cell antigen receptor, 26 we examined here whether Syk was recruited in lipid rafts upon PSGL-1 engagement.Our results show for the first ti...

Interactions between the leukocyte adhesion receptor L-selectin and P-selectin glycoprotein ligand-1 play an important role in regulating the inflammatory response by mediating leukocyte tethering and rolling on adherent leukocytes. In this study, we have examined the effect of post-translational modifications of PSGL-1 including Tyr sulfation and presentation of sialylated and fucosylated O-glycans for L-selectin binding. The functional importance of these modifications was determined by analyzing soluble L-selectin binding and leukocyte rolling on CHO cells expressing various glycoforms of PSGL-1 or mutant PSGL-1 targeted at Nterminal Thr or Tyr residues. Simultaneous expression of core-2 ␤1,6-N-acetylglucosaminyltransferase and fucosyltransferase VII was required for optimal L-selectin binding to PSGL-1. Substitution of Thr-57 by Ala but not of Thr-44, strongly decreased L-selectin binding and leukocyte rolling on PSGL-1. Substitution of Tyr by Phe revealed that PSGL-1 Tyr-51 plays a predominant role in mediating L-selectin binding and leukocyte rolling whereas Tyr-48 has a minor role, an observation that contrasts with the pattern seen for the interactions between PSGL-1 and P-selectin where Tyr-48 plays a key role. Molecular modeling analysis of L-selectin and Pselectin interactions with PSGL-1 further supported these observations. Additional experiments showed that core-2 O-glycans attached to Thr-57 were also of critical importance in regulating the velocity and stability of leukocyte rolling. These observations pinpoint the structural characteristics of PSGL-1 that are required for optimal interactions with L-selectin and may be responsible for the specific kinetic and mechanical bond properties of the L-selectin-PSGL-1 adhesion receptorcounterreceptor pair.Selectins play a major role in regulating leukocyte migration in inflammatory lesions by mediating leukocyte rolling along vascular wall at site of inflammation (1-8). L-selectin is expressed by most leukocytes whereas P-selectin and E-selectin expression is induced on activated platelets and/or endothelial cells (1,2,4,5,7,9). E-, P-, and L-selectin function at different although overlapping phases of the inflammatory reaction (10).P-selectin interacts with its major ligand P-selectin glycoprotein ligand-1 (PSGL-1) 1 and supports leukocyte rolling along postcapillary venules at the earliest phase of inflammation (11-13). Several studies have indicated that L-selectin mediates both primary leukocyte-endothelial interactions (14, 15) and secondary interactions between circulating and adherent leukocytes, which both participate in leukocyte recruitment in inflammatory lesions. Secondary interactions are mainly supported by the interaction of PSGL-1 with L-selectin (16 -18).PSGL-1 is a mucin-like glycoprotein expressed as a homodimer on leukocyte microvilli (4, 19 -21). P-selectin binds with relatively high affinity (K d ϳ300 nM) (22) to PSGL-1 by reacting with N-terminal tyrosine sulfate residues and with the sLe x tetrasaccharide determinants presented...

Asthma is a multifactorial and complex disease in which allergic factors and non-allergic triggers interact and result in bronchial obstruction and inflammation. Allergenic sensitization is important in the development of asthma and, although links between inhalant allergy and asthma have been known for many years, they have recently been re-emphasized. Indoor allergens are associated with asthma prevalence, severity and exacerbations whereas outdoor allergens such as pollens are associated with exacerbations. Moreover, there is a link between total IgE and asthma which appears to be independent of allergen sensitization. One of the typical aspects of airway inflammation of asthma is the infiltration of the airway wall by T helper type 2 (Th2) cells. These cells are attracted to inflammatory sites by adhesion molecules and chemokines among which CCR3 and CXCR4 receptors appear to be of importance. Differentiation of B cells into IgE-secreting plasma cells is a complex cascade of events in which cytokines play a crucial role. Both IL-4 and IL-13 are inducing IgE synthesis whereas IFN-gamma and IL-12 are blocking IgE synthesis. IgE production by B cells not only requires the presence of IL-4 or IL-13, but also a physical interaction between T and B cells, involving a number of surface and adhesion molecules such as CD40-CD40L and CD28/CD80. Production of TH2-cytokines is not restricted to T cells as basophils and mast cells can produce them indicating that these cells may be of importance in the synthesis of IgE.