Figure 3.

Sickle cell anemia-associated tissue factor production by monocytes in response to LPS is diminished by hydroxyurea treatment in vivo. (A) PBMC from sickle cell anemia patients were incubated with 100 ng/mL LPS in vitro and intracellular cytokine staining assay was performed to test whether hydroxyurea treatment in vivo induces changes in the capacity of monocytes to respond to LPS by producing tissue factor (TF). Data represent frequency of monocytes. HU group n = 17 and no HU group n = 20 At each experimental condition, the study groups were compared using the Mann-Whitney U test. **p < 0.01, ***p < 0.0001. (B) Mean Fluorescence Intensity (MFI) of TF expression by monocytes at indicated experimental conditions is shown. No statistically significant differences were observed. HU group n = 17 and no HU group n = 20. (C) Frequency of TF-expressing monocytes upon LPS stimulation was compared between SCA patients presenting or not previous occurrence of vaso-occlusive events (VOE). VOE group n = 11 and no VOE n = 26. The study groups were compared using the Mann-Whitney U test. *p < 0.05. (D) Receiver Operator Characteristics (ROC) curve analyses was employed to test whether frequency of TF-expressing monocytes after LPS stimulation could discriminate patients with previous occurrence of VOE from those who had not, as a way to measure strength of association. AUC, area under the curve. (E) Frequencies of TF-expressing monocyte subsets was compared were compared between the indicated groups using the Mann-Whitney U test. HU group n = 17 and no HU group n = 20. *p < 0.05, ** p < 0.01, ***p < 0.0001.