ALBERT

Description: Allograft transplantation requires chronic immunosuppression, but there is no effective strategy to evaluate the long-term maintenance of immunosuppression other than assessment of graft function. The ability to monitor naive alloreactive T cells would provide an alternative guide for drug therapy at early, preclinical stages of graft rejection and for evaluating tolerance-inducing protocols. To detect and quantify naive alloreactive T cells directly ex vivo, we used the unique ability of naive T cells to rapidly produce TNF-α but not IFN-γ. Naive alloreactive T cells were identified by the production of TNF-α after a 5-hour in vitro stimulation with alloantigen and were distinguished from effector/memory alloreactive T cells by the inability to produce IFN-γ. Moreover, naive alloreactive T cells were not detected in mice tolerized against specific alloantigens. The frequency of TNF-α–producing cells was predictive for rejection in an in vivo cytotoxicity assay and correlated with skin allograft rejection. Naive alloreactive T cells were also detected in humans, suggesting clinical relevance. We conclude that rapid production of TNF-α can be used to quantify naive alloreactive T cells, that it is abrogated after the induction of tolerance, and that it is a potential tool to predict allograft rejection.

Description: Systemic mastocytosis (SM) is a clonal myeloproliferative disease with variable clinical manifestations. The D816V mutation in the c-kit gene, present in over 90% of adult patients with SM, results in constitutive activation of the receptor tyrosine kinase and is believed to be related to disease pathogenesis. Although the majority of patients with SM lack peripheral blood eosinophilia, a subgroup exists and is classified as SM with eosinophilia (SM-eo). Recently, several reports of patients with SM-eo described the presence of either the Kit D816V mutation or the FIP1L1/PDGFRA fusion oncogene. Numerous similarities between patients with FIP1L1/PDGFRA and KIT D816V-associated peripheral blood eosinophilia have caused confusion about the management and specifically the role of imatinib in the treatment of these patients. It is of paramount importance to distinguish these two groups with pathologically similar, but molecularly and clinically distinct diseases. We thus compared the clinical, laboratory, and molecular features of 12 patients who met WHO criteria for SM (including presence of the D816V kit mutation) and had associated peripheral eosinophilia with those of 17 patients with peripheral eosinophilia and the FIP1L1/PDGFRA fusion oncogene (diagnosed with HES and evaluated at the same institution) and to the published reports of FIP1L1/PDGFRA-HES patients. Based on these comparisons, a number of clinical features appeared to be of potential use in distinguishing these two disorders. The presence of cardiac symptoms, a total serum tryptase under 60 ng/ml or the presence of either scattered mast cells or loose aggregates was found to be suggestive of FIP1L1/PDGFRA-associated disease. The presence of urticaria pigmentosa, a total serum tryptase over 150 ng/ml, the presence of dense mast cell aggregates and female sex were suggestive of Kit D816V-associated disease. To confirm and standardize this clinical classification, statistical methods were employed to test 21 possible risk factors for their ability to distinguish Kit and FIP1L1/PDGFRA-associated disease. Calculated risk factor scores were developed based on this analysis. Applying this risk factor based system, 16/17 FIP1L1/PDGFRA patients were classified correctly, with one patient neutral and all 12 Kit D816V SM-eo patients were classified correctly. Thirty four FIP1L1/PDGFRA patients in the literature were available for analysis, although all risk factors to create the score were not available for all patients. Despite this, 25/34 FIP1L1/PDGFRA patients were correctly predicted as FIP1L1/PDGFRA, 4/34 patients were neutral and 5/34 were misclassified as Kit D816V-associated SM-eo. These data suggest that the risk factor-based system presented in this study is useful in distinguishing imatinib-sensitive FIP1L1/PDGFRA-associated disease from imatinib-resistant Kit D816V-associated disease. Parameter SM-eo FIP1L1/PDGFRA HES Number patients 12 17 Male/Female 7/5 17/0 Cardiac symptoms 0/12 6/15 UP 7/12 0/15 Mean serum tryptase (ng/ml) 229 28 (n=13) Dense marrow aggregates 12/12 1/10

Description: Based on previous studies showing the efficacy of FactorIXa (FIXa) blockade using an active site-blocked form of this coagulation enzyme, we speculated that partial inhibition of the intrinsic coagulation pathway would offer a novel approach to attenuate intravascular clot formation without promoting untoward bleeding. Here we describe the anticoagulant activity of TTP889, a small molecule partial inhibitor of FIXa activity. TTP889 is orally absorbed with a PK profile that is conducive to once daily dosing. It is selective for FIXa in that it shows little to no activity against several other proteases in the clotting cascade including FXa, FXIa, FXIIa or FVIIa in a unique clotting assay. In vivo, TTP889 inhibited fibrin deposition in a rat arteriovenous (A/V) shunt model. In this model, vehicle treated rats had 104mg ± 43 of fibrin deposited on a silk thread after a 15 minute shunt while TTP889 treated rats had significantly less fibrin deposited (39mg ± 18 p=

Description: Human mast cells are found in skin and mucosal surfaces and next to blood vessels. They play a sentinel cell role in immunity, recognizing invading pathogens and producing proinflammatory mediators. Mast cells can recruit granulocytes, and monocytes in allergic disease and bacterial infection, but their ability to recruit antiviral effector cells such as natural killer (NK) cells and T cells has not been fully elucidated. To investigate the role of human mast cells in response to virus-associated stimuli, human cord blood–derived mast cells (CBMCs) were stimulated with polyinosinic·polycytidylic acid, a double-stranded RNA analog, or infected with the double-stranded RNA virus, reovirus serotype 3 Dearing for 24 hours. CBMCs responded to stimulation with polyinosinic·polycytidylic acid by producing a distinct chemokine profile, including CCL4, CXCL8, and CXCL10. CBMCs produced significant amounts of CXCL8 in response to low levels of reovirus infection, while both skin- and lung-derived fibroblasts were unresponsive unless higher doses of reovirus were used. Supernatants from CBMCs infected with reovirus induced substantial NK cell chemotaxis that was highly dependent on CXCL8 and CXCR1. These results suggest a novel role for mast cells in the recruitment of human NK cells to sites of early viral infection via CXCL8.

Description: Two adult patients with sickle cell anemia of blood group A and A2B respectively, received sufficient transfusions of group O blood to maintain nearly normal hemoglobin concentrations for 4 months or longer. Serial samples of the erythrocytes of each recipient were obtained by agglutination with anti-A (and anti-B) serum. The proportion of Hb F in the agglutinated erythrocytes was determined. Early in the transfusion period, a marked rise in the proportion of Hb F was noted. This rise was attributed to prolonged survival of erythrocytes which contained larger proportions of Hb F. In the later part of the transfusion period, the proportion of fetal hemoglobin declined to pre-transfusion levels or below. However, significant amounts of fetal hemoglobin in the erythrocytes of each patient were demonstrated throughout the period of study, and Fe59 incorporation into Hb F in vivo was demonstrated in one patient after 4 months of transfusion therapy. Under the conditions of these studies, synthesis of Hb F continued despite prolonged correction of the anemia. A decline in the proportion of Hb F in the erythrocytes of one patient after 5 months of transfusions suggested that Hb F synthesis may ultimately be depressed by transfusions. It was suggested that the proportion of fetal hemoglobin observed in the erythrocytes might in certain diseases reflect the degree of anemia present many months before.

Description: Background: Peripheral Blood Progenitor Cells (PBPC) cryopreserved in DMSO are thawed at the patient’s bedside and infused immediately. Usually the infusions are completed without incident. There are occasions when mild/severe transfusion related reactions occur. When this does occur, the infusion is either slowed or paused for a short period of time. When reactions are severe enough to warrant stoppage of the infusion, transplant facilities maybe faced with discarding any remaining thawed cells. We have explored the question of salvaging the remaining cells by re-cryopreservation using two cryopreservation methods. Study Design: Twenty PBPC were thawed in a 37C water bath until the internal temperature of the cells was approx 2-6C. The PBPC were not washed and allowed to remain at room temperature for 15 minutes. Ten PBPC were then placed on ice for 45 minutes. This simulated the transfer of cells to an off-site cryopreservation lab. These cells were then transferred to a new cryo bag, no change in the cryoprotectant solutions, and placed into a rate controlled freezer (RCF) bringing their temperature back to

Description: A new unstable hemoglobin variant, hemoglobin Gun Hill, is reported. Two members of a Caucasian family were found to be heterozygous for the abnormal hemoglobin. Evidence of mild chronic hemolysis was found in both individuals. Heinz-Ehrlich bodies were absent from the peripheral blood of the patients with hemoglobin Gun Hill, but Heinz-like inclusions were readily produced in their red cells upon in vitro incubation with the redox dyes brilliant cresyl blue or new methylene blue. Precipitation of hemoglobin occurred when solutions of hemoglobin Gun Hill were exposed to the dyes or were heated to 50 C. Previous studies have shown that there is a deletion of five amino acids in the β chains of hemoglobin Gun Hill. This results in impaired heme binding, and the abnormal molecule lacks half the expected number of heme groups. These structural alterations are probably responsible for the instability of the abnormal hemoglobin. Studies of the relative rates of synthesis of hemoglobins A and Gun Hill, using in vitro and in vivo technics, indicated an increased turnover rate for the variant protein. The evidence also suggested that hemoglobin Gun Hill is synthesized more rapidly than hemoglobin A.

Description: Although imatinib is clearly the treatment of choice for FIP1L1/PDGFRA-positive chronic eosinophilic leukemia (CEL), little is known about optimal dosing, duration of treatment, and the possibility of cure in this disorder. To address these questions, 5 patients with FIP1L1/PDGFRA-positive CEL with documented clinical, hematologic, and molecular remission on imatinib (400 mg daily) and without evidence of cardiac involvement were enrolled in a dose de-escalation trial. The imatinib dose was tapered slowly with close follow-up for evidence of clinical, hematologic, and molecular relapse. Two patients with endomyocardial fibrosis were maintained on imatinib 300 to 400 mg daily and served as controls. All 5 patients who underwent dose de-escalation, but neither of the control patients, experienced molecular relapse (P 〈 .05). None developed recurrent symptoms, and eosinophil counts, serum B12, and tryptase levels remained suppressed. Reinitiation of therapy at the prior effective dose led to molecular remission in all 5 patients, although 2 patients subsequently required increased dosing to maintain remission. These data are consistent with suppression rather than elimination of the clonal population in FIP1L1/PDGFRA-positive CEL and suggest that molecular monitoring may be the most useful method in determining optimal dosing without the risk of disease exacerbation. This trial was registered at http://www.clinicaltrials.gov as no. NCT00044304.

Description: A Jewish family in which Hb L Ferrara (α247 Asp → Gly β2) occurred is reported. Studies of some of the properties of this hemoglobin demonstrated that its oxygen equilibria, number of readily reactive-SH groups, and spectro-photometric tyrosine titration were indistinguishable from Hb A. Nevertheless, Hb LF was more unstable than Hb A at 55 C. The propositus had accelerated blood destruction although six other heterozygotes for Hb LF did not. A second defect in red cell enzymes or red cell lipids of the propositus was not demonstrable with the technics used but the possibility that the simultaneous occurrence of Hb LF and an otherwise "silent" red cell defect may lead to a hemolytic state remains an attractive explanation. The data provided by this family study did not permit a definite conclusion about the relationship of clinically evident hemolysis in the propositus to the presence of the abnormal hemoglobin.

Description: Several compounds currently in development for the treatment of thrombotic disorders demonstrate high levels of specificity for single targets of the blood coagulation cascade such as factor Xa and thrombin. However, development of a single molecule dual inhibitor against factor Xa and thrombin may expand the efficacy to safety ratio of treatment options for arterial and venous thrombosis. The objective of this study was to determine if simultaneous administration of PD 0313052, a selective Xa inhibitor and argatroban, a direct thrombin inhibitor, would lead to a synergistic antithrombotic effect in a rabbit AV shunt model of thrombosis. Intravenous administration of PD 0313052 alone at doses of 0.1, 0.3, and 1.0 mg/kg/min resulted in thrombus weight (TW) reductions of 11±3, 25±10 and 67±7 % compared to the vehicle group. Argatroban at 1, 3 and 10 mg/kg/min reduced TW 16±13, 47±10 and 75±6 %. When PD 0313052 was administered at 0.1 mg/kg/min in combination with argatroban at 1, 3 or 10 mg/kg/min TW was reduced 50±7, 60±7 and 82±9 %. Likewise, argatroban at 1 mg/kg/min combined with 0.1, 0.3 or 1mg/kg/min of PD 0313052 resulted in TW reductions of 56±9, 60±9 and 84±5 %, respectively. At the lowest combined doses of PD 0313052 and argatroban there was no change in bleeding time relative to the additive fold-increases from each drug alone. The EC50 of intravenously administered PD 0313052 and argatroban was 67±23 and 178±58 ng/ml, respectively. When the drugs were combined the EC50 was reduced to 12±6 ng/ml with the PD 0313052/argatroban combination and to 83±29 ng/ml with the argatroban/PD 0313052 combination. A synergistic effect was also observed in an ex vivo assay of thrombin generation (TG). Predicted additive inhibition of TG based on the individual effects of each compound was −9±7, 9±2 and 29±7 % compared to 10±5, 32±5 and 55±3 % with the 313052/argatroban combination. The predicted effects of the argatroban/PD 0313052 combination was −9±7, 1±7 and 16±9 % compared to the actual inhibition of 5±3, 14±5 and 31±7 %. These results demonstrate a significant synergistic antithrombotic effect by combining low doses of a factor Xa and a thrombin inhibitor and support the hypothesis that development of a single molecule inhibitor against different hemostatic targets may offer greater efficacy in the prevention and treatment of venous and arterial thrombosis.