Immunological and Antiviral Responses After Therapeutic DNA Immunization in Chronic Hepatitis B Patients Efficiently Treated by Analogues

A substudy of a phase I/II, prospective, multicenter clinical trial was carried out to investigate the potential benefit of therapeutic vaccination on hepatitis B e antigen-negative patients with chronic hepatitis B (CHB), treated efficiently with analogues. Patients were randomized in 2 arms, one receiving a hepatitis B virus (HBV) envelope DNA vaccine, and one without vaccination. At baseline, HBV-specific interferon (IFN)-γ–producing T cells were detected in both groups after in vitro expansion of peripheral blood mononuclear cells. Vaccine-specific responses remained stable in the vaccine group, whereas in the control group the percentage of patients with HBV-specific IFN-γ–producing T cells decreased over time. The vaccine-specific cytokine-producing T cells were mostly polyfunctional CD4⁺ T cells, and the proportion of triple cytokine-producer T cells was boosted after DNA injections. However, these T-cell responses did not impact on HBV reactivation after stopping analogue treatment. Importantly, before cessation of treatment serum hepatitis B surface antigen (HBsAg) titers were significantly associated with DNA or HBsAg clearance. Therapeutic vaccination in CHB patients with persistent suppression of HBV replication led to the persistence of T-cell responses, but further improvements should be searched for to control infection after treatment discontinuation.     

Chemoattractant-induced changes in surface expression and redistribution of a functional ligand for P-selectin on neutrophils

Adhesion between platelets and neutrophils is mediated through the interaction of P-selectin on activated platelets with a carbohydrate- containing structure on neutrophils, and occurs under both static and shear conditions. Recent studies using flow chambers have shown that neutrophils become activated after binding to surface-adherent platelets expressing P-selectin. The objective of the present study was to investigate the effect of such activation on the interactions of platelet P-selectin with its ligand on neutrophils. Flow cytometric analyses using P-selectin chimeras revealed that activation induced a rapid and marked reduction in chimera binding, with levels of binding decreased by 71% after 15 minutes of stimulation with the chemotactic agent, FMLP. Using a visual assay of platelet-neutrophil rosetting, we showed that the P-selectin ligand was translocated and clustered at the uropod of neutrophils following the shape changes and polarization induced by chemotactic stimulation. Activated neutrophils bound to surface-adherent platelets also displayed the clustering of P-selectin ligand at the uropod, and these neutrophils detached from the platelets when a shear stress (2 dynes/cm2) was applied through the adhesion chamber. These results indicate that chemotactic stimulation of neutrophils induces changes in the surface expression and distribution of a biologically relevant ligand for P-selectin, and that these changes might influence the adhesive interactions occurring between neutrophils and activated platelets.     

Hepatitis C virus infection and chronic liver disease in children with leukemia in long-term remission

Antibody to the recently identified hepatitis C virus (HCV) was investigated in sera of 50 leukemic children who had chronic liver disease (CLD), observed for 1 to 12.6 years after therapy withdrawal. All patients were tested for anti-HCV at regular intervals: Ortho- enzyme-linked immunosorbent assay (ELISA) test was performed in all cases. Reactive sera were also tested by recombinant immunoblotting assay to define the specificity of the results obtained by ELISA. Twelve cases (24%) were persistently positive (group A), 11 (22%) were transiently anti-HCV+ positive (group B), and 27 (54%) were negative. Mean SGPT peak during follow-up was significantly higher in group A (P = .014, A v B and P less than .00001, A v C). SGPT normalized off- therapy in 1 of 12 cases (group A), 10 of 11 (group B), and 19 of 27 (group C) (P = .0004, A v B and P = .012, A v C). Accordingly, liver histology, available in 37 patients, showed signs of chronic hepatitis in all patients in group A while most patients in group B and C had less severe liver lesions. These results indicate that HCV plays a significant role in the etiology of chronic hepatitis in leukemic patients and that persistent anti-HCV activity correlates with a more severe CLD, which could jeopardize the final prognosis of children cured of leukemia.     

Echo contrast agents improve flow display of color Doppler: in vitro studies

Flow detection by color Doppler is impaired by low velocity of flow and increasing attenuation and depth of ultrasound penetration. The effects of increased echogenicity on flow detection (Toshiba SSH 65A) were thus studied in a flow model, which yielded similar strengths of Doppler signals as seen in the clinical routine, by adding microbubble solutions to the blood analog fluid (45% aqueous glycerin) and comparing signal strength (score 0-5) prior to and after contrast. The flow within the plexiglass tube with less than 3 degrees angle of coincidence for Doppler interrogation was laminar with a parabolic velocity profile at physiological velocities and pressures. In comparison with various contrast agents at a flow velocity of 18 cm/sec and 19 dB attenuation, flow was not detectable in control color Doppler, after 4 mL of the blood analog fluid, and after 4 mL of an agitated saline solution 9 mg/mL, but visible after 4 mL of Echovist, a polysaccharide solution with reproducible bubble size and concentration and after 4 mL of an agitated polygelatin solution. Increasing concentration of Echovist (50-400 mg/mL) improved flow detection. Echovist 200 mg/mL enhanced the score by 1.1 + -0.6 for velocities 5-20 cm/sec (P less than 0.01), by 1.6 + -0.8 for 40-100 cm/sec (P less than 0.001), and by 1.1 + -0.6 for velocities greater than 150 cm/sec (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)