Figure 6
Epinephrine-activated SS RBCs adhere through LW and induce activation and adhesion of murine leukocytes. (A-B) Epinephrine-induced SS RBC adhesion and vaso-occlusion are mediated via LW. (A) Inhibition of SS RBC adhesion with soluble proteins was performed as described in “Material and methods.” Sham-treated SS RBCs showed little adhesion to vessel walls, whereas epi-treated SS RBCs showed marked adhesion to postcapillary venules, with intermittent vaso-occlusion. Infusion of sCD44 (as a negative control) 30 minutes prior to intravenous administration of epi-treated SS RBCs (n = 5) had no effect on epi-treated SS RBC adhesion to postcapillary venules, whereas infusion of sLW 30 minutes prior to injection of epi-treated SS RBCs (n = 5) markedly inhibited adhesion to postcapillary vessels. (B) Involvement of LW in SS RBC adhesion to endothelium and vaso-occlusion. Animals were infused with sham- or epi-treated SS RBCs 30 minutes after intravenous administration of sCD44 or sLW (n = 5 for each treatment). Thirty segments of venules were analyzed to quantify the length of venules occupied by SS RBCs. The values were averaged among groups of animals to represent the mean percent venular length occupied by SS RBCs. Error bars show SEM of 5 different experiments. *P < .001 compared with sCD44/epi-treated (animals/cells) for vessels up to 25 μm in diameter, and P < .05 for vessels more than 25 μm in diameter. (C) Epi-activated human SS RBCs induce adhesion of murine leukocytes to endothelium. Fluorescently labeled (red) sham- (n = 3) and epi-treated SS RBCs (n = 3) were infused 30 minutes after injection of rat FITC-labeled antimouse CD45 or LFA-1 antibodies. In the presence of epi-treated human SS RBCs, murine leukocytes adhered to postcapillary endothelium, and this adhesion was blocked by antibody against mouse LFA-1. Arrows indicate identical areas visualized with filters for red and green fluorescence to show where human SS RBCs and murine leukocytes are adherent to endothelium. In some areas, both murine leukocytes and human SS RBCs were adherent, whereas in other areas only one adherent cell type was present. Top panels show adhesion of human SS RBCs, bottom panels show adhesion of murine leukocytes.

Epinephrine-activated SS RBCs adhere through LW and induce activation and adhesion of murine leukocytes. (A-B) Epinephrine-induced SS RBC adhesion and vaso-occlusion are mediated via LW. (A) Inhibition of SS RBC adhesion with soluble proteins was performed as described in “Material and methods.” Sham-treated SS RBCs showed little adhesion to vessel walls, whereas epi-treated SS RBCs showed marked adhesion to postcapillary venules, with intermittent vaso-occlusion. Infusion of sCD44 (as a negative control) 30 minutes prior to intravenous administration of epi-treated SS RBCs (n = 5) had no effect on epi-treated SS RBC adhesion to postcapillary venules, whereas infusion of sLW 30 minutes prior to injection of epi-treated SS RBCs (n = 5) markedly inhibited adhesion to postcapillary vessels. (B) Involvement of LW in SS RBC adhesion to endothelium and vaso-occlusion. Animals were infused with sham- or epi-treated SS RBCs 30 minutes after intravenous administration of sCD44 or sLW (n = 5 for each treatment). Thirty segments of venules were analyzed to quantify the length of venules occupied by SS RBCs. The values were averaged among groups of animals to represent the mean percent venular length occupied by SS RBCs. Error bars show SEM of 5 different experiments. *P < .001 compared with sCD44/epi-treated (animals/cells) for vessels up to 25 μm in diameter, and P < .05 for vessels more than 25 μm in diameter. (C) Epi-activated human SS RBCs induce adhesion of murine leukocytes to endothelium. Fluorescently labeled (red) sham- (n = 3) and epi-treated SS RBCs (n = 3) were infused 30 minutes after injection of rat FITC-labeled antimouse CD45 or LFA-1 antibodies. In the presence of epi-treated human SS RBCs, murine leukocytes adhered to postcapillary endothelium, and this adhesion was blocked by antibody against mouse LFA-1. Arrows indicate identical areas visualized with filters for red and green fluorescence to show where human SS RBCs and murine leukocytes are adherent to endothelium. In some areas, both murine leukocytes and human SS RBCs were adherent, whereas in other areas only one adherent cell type was present. Top panels show adhesion of human SS RBCs, bottom panels show adhesion of murine leukocytes.

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