Tissue factor-positive monocytes in children with sickle cell disease: relation to vaso-occlusive crisis

Background Hemostatic abnormalities are well documented in sickle cell disease (SCD). Nevertheless, whether these perturbations could contribute toward sickle vasculopathy is still not clear. Aim To evaluate tissue factor (TF) expression (CD142) on monocytes in children with SCD and correlate the results with the clinical state and some inflammatory and coagulation activation markers. Patients and methods This study included 24 children with SCD in steady state, 24 in painful crisis, and 20 healthy age-matched and sex-matched children as controls. The relevant data including the pain rate were retrieved from patients’ files. For each participant, complete blood count, prothrombin time (PT%), activated partial thromboplastin time (aPTT), fibrinogen, d-dimer, thrombin–antithrombin complex, and quantitative C-reactive protein were assayed. TF expression on monocytes was analyzed by flow cytometry. Results TF-positive monocytes were significantly higher in both patient groups compared with the controls, being higher in patients in painful crisis (2.06 ± 0.64, 8.01 ± 1.53, and 13.5 ± 4.3 for the controls, steady-state group, and the painful crisis group, respectively, P 0.0001 in all comparisons). The same pattern was found for all tested inflammatory and coagulation markers, except PT and aPTT. In the painful crisis group, TF monocytes expression was correlated positively with the pain rate and all markers of inflammation and coagulation, except PT, aPTT, and thrombin–antithrombin complex, with an inverse correlation with hemoglobin and red blood cells. Conclusion Collectively, these results confirm the prognostic significance of evaluation of TF-positive monocytes in SCD children.