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Complement is involved in sickle red cell adhesion
Factor H and its 19-20 domain normalize the sickle red blood cell trajectory and transverse velocity on tumor necrosis factor-α-activated vascular endothelium
We then developed a new algorithm for RBC to analyze their trajectory and transverse velocity, the velocity com- ponent perpendicular to the direction of flow of the RBC
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during their transit in the flow-chamber. The trajectory of each sickle RBC appeared irregular in space and was not uniform in time, especially when compared to that of healthy RBC (Figure 4A,B). This observation was based on the high transverse displacement and the presence of fre- quent stop-and-go motion that characterized the sickle RBC transit on the activated vascular endothelium. The
Figure 2. Adhesion of red blood cells to endothelium activated or not by tumor necrosis factor-a. (A) Adhesion of healthy (AA) or sickle cell disease (SCD) red blood cells (RBC) on immortalized endothelium (EA926.hy) treated or not with tumor necrosis factor-a (TNF-a) under flow conditions (data are expressed as cells/mm2). The data were obtained from six separate comparable experiments. All calculations were performed using the IBM SPSS 20.0 statistical package (IBM Inc., Armonk, NY, USA). The results of the adhesion tests are expressed as median values with the minimum-maximum range and are illustrated by box plots. The data were ana- lyzed with non-parametric tests, the Mann-Whitney U test for unpaired samples and the Wilcoxon signed-rank test for paired samples. A value of P<0.05 is considered statistically significant. (B) Dose-response curve for factor H (FH) in adhesion assays for healthy (AA) or sickle (SCD) RBC. Data were obtained at 6 min flux on endothelium treated with either vehicle or TNF-a. The curves are representative of six separate and independent experiments with similar results.
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Figure 3. Factor H and its 19-20 segment normalized the transit of sickle red blood cells on the tumor necrosis factor-α-activated vascular endothelial surface. (A) Sickle cell adhesion after 6 min of perfusion on activated or non-activated endothelium (±TNF-a) in the presence of FH 9 nM or 18 nM final concentration. The data shown are representative of six other independent assays with similar results. Wilcoxon test: *indicates the corresponding significance. A P value <0.05 is considered statistically significant. Statistical analysis as in Figure 2A. (B) Sickle cell adhesion after 6 min of perfusion on activated or non-activated endothelium (± TNF-a) in the presence of FH and its fragments 19-20 and 6-8 (18 nM final concentration). Data shown are representative of six other independent assays with similar results. A P value <0.05 is considered statistically significant. Statistical analysis as in Figure 2A.
haematologica | 2019; 104(5)
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