Cellular immune response to hepatitis C virus (HCV) in nonviremic blood donors with indeterminate anti-HCV reactivity

BACKGROUND: Blood donors with indeterminate hepatitis C virus antibody (anti-HCV) reactivity are rejected from blood donation. As they are mostly nonviremic, the source of these reactions remains unclear. Reasons for such findings can be resolved HCV infections as well as unspecific antibody reactions. The aim of this study was to investigate HCV-specific T-cell response in blood donors to determine the reason for the weak antibody detection.
STUDY DESIGN AND METHODS: Anti-HCV reactivity was tested in 72 blood donors initially diagnosed with an indeterminate HCV result by enzyme-linked immunosorbent assay and immunoblot. Cellular immune response was measured by proliferation assay and enzyme-linked immunosorbent spot analysis after stimulation with viral proteins core, NS3, and NS4.
RESULTS: In 56% of donors anti-HCV reactivity was detectable in the screening assay whereas 72% had a reaction in the confirmation immunoblot. Forty-six percent of donors had a cellular immune response against HCV proteins. The response was most frequent to NS3 protein.
CONCLUSION: In almost half of donors the indeterminate result in serologic testings could be explained by a previous resolved HCV infection as the pattern of T-cell response was similar to these patients. These findings indicate that HCV-specific antibodies disappear more rapidly after resolved infection than HCV-specific T cells. These results are important for counseling blood donors and patients with indeterminate serologic results.     

Erythrocytic precursor cells show potent shear stress resistant adhesion and home to hematopoietic tissue in vivo

BACKGROUND: Transfusion of erythropoietic precursor cells has been suggested as an alternative to conventional red blood cells. However, little is known about the fate of transfused erythrocytic precursors after they enter the bloodstream.
STUDY DESIGN AND METHODS: Erythrocytic precursors were classified by flow cytometry into different maturation stages. Precursors were enriched using cell surface expression of CD71 and Ter119 antigens and analyzed under shear stress in a parallel plate flow chamber and after fluorescence tagging with PKH and transfusion into anemic mice.
RESULTS: We found that at all maturation stages, erythrocytic precursors expressed the adhesion receptor very late antigen (VLA)-4 with a frequency decreasing from 90% to approximately 60% during maturation. In contrast, expression of the β₂-integrins LFA-1 and Mac-1 and the rolling receptor P-selectin glycoprotein ligand-1 increased from 10% to 20% to approximately 50% during erythrocytic maturation. The chemokine receptor CXCR4 was expressed at low levels during differentiation stages. In vitro shear stress adhesion analysis showed that erythrocytic precursors can efficiently activate VLA-4 such that it binds its cognate ligand, vascular cell adhesion molecule (VCAM)-1. The coimmobilization of stromal cell–derived factor-1α with VCAM-1 strengthened this adhesion. Transfusion of primitive (CD71+) or more mature (Ter119+) erythrocytic precursors into mice showed that both populations selectively and efficiently home to hematopoietic tissues.
CONCLUSION: Our results demonstrate that erythrocytic precursor cells of different maturation stages are capable of homing to hematopoietic organs. This work has implications for the development of transfusion protocols that use ex vivo expanded, but not fully matured, erythrocytic precursors from cultured stem cell populations.     

Current developments in thrombolytic therapy using novel plasminogen activators

As a result of intensive recent research, the molecular mechanisms governing the human fibrinolytic system could be elucidated. Clinical trials using streptokinase and urokinase demonstrated that therapeutic thrombolysis is a valuable regimen in the treatment of patients with thromboembolic diseases. After unsuccessful attempts to increase the clot specificity of these agents, efforts were increased towards developing fibrin-specific substances with high thrombolytic potency and negligible effects on systemic hemostasis. Tissue-type plasminogen activator manufactured by recombinant DNA technology (rt-PA) is currently the most comprehensively investigated fibrin-specific thrombolytic agent with the most clearly understood mechanism of action in vivo. Pro-urokinase has also become available through biotechnology. A large number of clinical trials studying thrombolytic therapy of myocardial infarction have proved that intravenous rt-PA posesses superior efficacy compared to conventional fibrinolytic agents. Comparatively few clinical studies have been performed using pro-urokinase. At therapeutic doses, the fibrin specificities of these agents differ. So far it has not been possible to correlate the incidence of bleeding complications during fibrinolytic therapy with alterations in hemostasis parameters. For routine laboratory monitoring of thrombolysis the determination of fibrinogen and thrombin clotting time can be recommended. New developments with potential for yielding the next generation of thrombolytic agents are mutants and chimeras of t-PA and pro-urokinase, and conjugates of these substances with fibrin specific antibodies.     

Blood screening for influenza

Influenza viruses, including highly pathogenic avian influenza virus (H5N1), could threaten blood safety. We analyzed 10,272 blood donor samples with a minipool nucleic acid amplication technique. Analytical sensitivity of the method was 804 geq/mL and 444 geq/mL for generic influenza primers and influenza (H5N1) subtype-specific primers. This study demonstrates that such screening for influenza viruses is feasible.     

Impact of leukapheresis on early death rate in adult acute myeloid leukemia presenting with hyperleukocytosis

BACKGROUND: Patients with acute myeloid leukemia (AML) with hyperleukocytosis of at least 100 x 10(9) per L are at high risk of early death due to pulmonary or cerebral leukostasis. Although the efficacy of leukapheresis in terms of prompt cytoreduction is generally accepted, published data regarding the clinical value of immediate therapeutic leukapheresis are limited and conflicting. STUDY DESIGN AND METHODS: To determine whether leukapheresis has a favorable impact on early mortality, the clinical course of 53 newly diagnosed patients with AML and hyperleukocytosis admitted between 1995 and 2005 was analyzed retrospectively. Before August 2001, 28 patients received chemotherapy without leukoreduction (Cohort A). Thereafter, all AML patients with hyperleukocytosis were scheduled to receive leukapheresis, which was performed in 25 patients (Cohort B). RESULTS: There were no procedure-related adverse events. By Day 21 of therapy, 13 of 53 patients had died, resulting in an overall early death rate of 25 percent. In a multivariate logistic regression model, patients in Cohort B had a significantly lower risk of early death than patients in Cohort A (16% vs. 32%, respectively; p = 0.015). Dyspnea (p = 0.005), elevated creatinine (p = 0.028), and higher lactate dehydrogenase serum levels (p = 0.021) were independent risk factors for early death. With a median follow-up of 24.2 months, the overall survival was similar in both cohorts (Cohort A, 7.5; Cohort B, 6.5 months). Thus, leukapheresis had no impact on patients' long-term survivals. CONCLUSIONS: Our experience suggests that AML patients with hyperleukocytosis receiving leukapheresis had a significantly lower risk for early death by Day 21 than patients treated without leukapheresis. We therefore have adopted leukapheresis as a standard procedure in our department.