Lowered free protein s and thrombosis in systemic lupus erythematosus patients

الملخص EN

Objective: Thrombosis is a relatively common complication in systemic lupus erythematosus (SLE) patients.

It is strongly associated with the presence of antiphospholipid antibodies (aPL).

The mechanism involved in the pathogenesis of this prothrombotic state remains obscure.

Material & Methods: We studied 25 SLE patients and 10 healthy individuals age and sex matched as a control group.

Plasma samples were assayed for free protein S and correlated to the level of prothrombin fragments (F1+2) and lipoprotein (a) in conjunction with the presence of lupus anticoagulant (LAC) and anti-phospholipid antibodies.

Results: Functional assay for anticoagulant proteins (protein C, Antithrombin 111 and plasminogen) were in the normal range in all patients.

We found 9/25 patients with LAC, 2/25 with LAC and aPL, 12/25 with aPL and 2 patients with normal free protein S were negative for both aPL and LAC.

A low level of free protein S was found in 12 patients (48%).

Out of these, 4 patients (31%) with LAC & 8 patients with aPL (67%).

Four out of 12 (33%) patients with lowered free protein S had history of thrombosis.

The mean serum level of lipoprotein (a) in patients with lowered free protein S was higher than in those with normal free protein S (93+12 vs.

31+8; p<0.001).

The mean level of F1+2 was significantly higher (1.45+0.42 vs.

0.99+0.16; p<0.05) and the mean serum D-diamer was lower (349+118 vs.

475+123; p<0.001) in study patients with reduced free protein S levels than those with normal levels.

Conclusion: Thrombin generation was more evident among SLE patients with aPL antibodies and reduced free protein S levels than SLE patients with aPL antibodies and normal free protein S levels.