ADHESION OF SICKLE RED-BLOOD-CELLS AND DAMAGE TO INTERLEUKIN-1-BETA STIMULATED ENDOTHELIAL-CELLS UNDER FLOW IN-VITRO

Two factors that are hypothesized to contribute to vasoocclusive crise s in sickle cell anemia are increased sickle red blood cell-endothelia l cell interactions and damage to endothelium. Despite considerable st udy, the mechanisms by which erythrocyte-endothelial interactions occu r and the role of endothelial damage have not yet been fully elucidate d. In this report, we demonstrate that adhesion and damage may be rela ted in a model of vasoocclusion in sickle cell anemia. Phase contrast microscopy coupled to digital image processing was used to determine t he adhesion of sickle red blood cells to 1-, 4-, and 24-hour interleuk in-1 beta (IL-1 beta) stimulated endothelial cells in a parallel plate flow chamber. Morphological alterations to activated endothelial cell s after the perfusion of sickle erythrocytes were also identified. Pre treatment of monolayers with 50 pg/mL of IL-1 beta for 1, 4, and 24 ho urs caused approximately 16-fold increases in adhesion of sickle cells to activated endothelium at all time points. Results with an Arginine -glycine aspartic acid (RGD) peptide and monoclonal antibodies indicat ed a role for three different endothelial cell receptors: alpha(v) bet a(3) after 1 hour of IL-1 beta stimulation; E-selectin after 4 hours o f IL-1 beta stimulation; and vascular cell adhesion molecule-1 after p rolonged exposure to cytokines. Perfusion of sickle, but not normal, e rythrocytes resulted in alteration of endothelial morphology. Approxim ately 6% to 8% damage was observed on 4- and 24-hour IL-1 beta stimula ted endothelial cells after the perfusion of sickle cells. Damage to 2 4-hour activated endothelial cells showed a positive correlation (r = .899) with the number of adherent sickle erythrocytes. (C) 1996 by The American Society of Hematology.