BLOOD PROTEIN-C AND PROTEIN-S IN SICKLE-CELL DISEASE

Proteins C and S are vitamin K-dependent proteins with an essential an ticoagulant function. Protein C exists in an inactive form and is acti vated by a thrombin-thrombomodulin complex. Protein S combines with pr otein C and forms a stoichiometric complex which regulates coagulation in the presence of calcium. As patients with sickle cell disease (SCD ) bear a high risk of developing thrombo-embolic disorders, we studied the coagulation derangement in 100 patients and 40 normal age- and se x-matched controls. The patients were clinically assessed and classifi ed into sickle cell homozygotes (Hb SS), Hb S heterozygotes (Hb AS) an d double heterozygotes for Hb S/beta(0)-thalassaemia based on haematol ogical parameters, red cell indices, Hb A(2) and F levels and genetic studies. The proteins C and S were estimated and related to the type o f the gene defect. The results showed significantly reduced levels of proteins C and S in SCD patients with the highest prevalence of defici ency in patients with a severe disease and frequent episodes of crisis . However, no significant differences were encountered in the level of proteins C and S in the same patients during the steady state and dur ing episodes of crisis. It was concluded that the lower protein C and S levels in SCD is either due to decreased production or increased con sumption though this reduction does not seem to play a role in produci ng thrombo-embolic disorders.