ABSTRACT
To investigate the possible role of the erythrocyte adhesion marker [CD36] in modulating adhesion of sickle erythrocytes to vascular endothelium and its relation to HbF% and hydroxyurea [HU] therapy, 28 pediatric sickle cell anemia [SCA] patients, divided into 3 groups, were studied. Group I included 11 patients in a steady state; group II comprised 10 patients in a steady state receiving HU and group III involved 7 patients in acute painful crises. Ten healthy age matched children served as controls. CD36+ erythrocytes were assessed using flow cytometry and expressed as % of positive cells. HU-treated patients [Group II] improved clinically and hematologically even before the peak level of HbF were reached. The mean Hb, Ht and RBCs were higher in-group II VS groups I and III [P < 0.05] and the WBCs and platelet counts of group II were comparable to controls. HbF%, was significantly higher in group II VS groups I and III [P < 0.001]. The mean [336% was significantly elevated in every patient group compared to controls [P< 0.001]. In-group II, it was 1.35 +/- 0.3% which was lower than group I and higher than group III [2.75 +/- 1.4, 0.9 +/- 0.1 7, P < 0.01]. 036% was positively correlated to reticulocyte % [r = 0.894, P = 0.000] being two faces of the same coin in vaso-occlusion. Also there was an inverse significant relationship between CD36% and HbF% [r -0.569, P < 0.007]. In addition a strong positive correlation was found between CD36% and duration of HU therapy [r = 0.767, P < 0.01]. This could be a form of drug tolerance over-time
Conclusion: more therapeutic modalities are needed to tackle more effectively the prime pathogenetic mechanism of vaso-occlusion as CD36 in SCA children