Determination of the lifespan of erythrocytes from greyhounds, using an in vitro biotinylation technique.

OBJECTIVE: To determine the RBC lifespan of Greyhounds, using an in vitro labeling technique. DESIGN: RBC from dogs were labeled with NHS-biotin and their disappearance measured over time to determine RBC lifespan. SAMPLE POPULATION: 5 Greyhounds that had been vaccinated against distemper, adenovirus 1 and 2 infections, parainfluenza, leptospirosis, parvovirus, and coronavirus infections, Bordetella bronchiseptica infection, and rabies the previous year; 3 sexually intact 14-month-old Beagles served as controls. PROCEDURE: After venipuncture for CBC, catheters were inserted in the cephalic vein of each dog. Butorphanol was then administered to achieve mild sedation and analgesia, and glycopyrrolate was administered to ensure maintenance of adequate heart rate during phlebotomy. Dogs were positioned in lateral recumbency; blood was removed via jugular venipuncture, using a standard laboratory donor blood bag containing citrate-phosphate-dextrose solution. Blood was transferred aseptically into sterile polystyrene containers and NHS-biotin was added. After incubation, the labeled RBC were reinfused into the dogs and the blood was allowed to recirculate for 1 hour before the first postinfusion sample was taken. At frequent intervals, blood to be analyzed was taken by jugular venipuncture, and the percentage of labeled cells was determined by flow cytometry. RESULTS: The mean RBC lifespan of non-Greyhounds was significantly longer than that of Greyhounds (104.3 +/- 2.2 days vs 53.6 +/- 6.5 days; P = 0.001). A negative linear correlation was also found between age of the Greyhounds and their RBC lifespan (P = 0.01, R2 = 0.91). CONCLUSIONS: The shorter RBC lifespan of the Greyhounds may explain the finding of macrocytosis reported in earlier work. The reason for the shorter RBC lifespan in Greyhounds may be caused by differences in Greyhound RBC membrane structure or accelerated RBC removal from the circulation.

TNF-alpha suppresses IL-1 alpha and IL-6 upregulation of C4b-binding protein in HepG-2 hepatoma cells.

C4b-binding protein (C4BP) is a regulatory protein involved in the regulation of the classical pathway of complement and the natural anticoagulant pathway. C4BP is synthesized by the liver, a target organ of the IL-6 proinflammatory cytokine. C4BP is an acute-phase protein and its basal levels may increase by as much as 4-fold during an inflammatory response. IL-6 which plays a major role in the modulation of the acute-phase proteins, including C4BP, also has been shown by our group to significantly increase hepatocyte production of the anticoagulant protein, protein S. In this study, we have examined the role of cytokine combinations on the production of the C4BP regulatory protein in the HepG-2 hepatoma cell line and report that IL-1 alpha and IL-6 in combination as well as IL-1 alpha and Oncostatin M (OSM) were approximately additive in the upregulation of C4BP while IL-6 and OSM were not and that TNF-alpha blocked both IL-1 alpha and IL-6 but not OSM upregulation of C4BP.