Protein C activity in patients with antiphospholipid syndrome.
The interaction between antiphospholipid antibodies and the protein C system may explain at least a part of the mechanisms underlying thrombosis in the antiphospholipid syndrome (APS). We evaluated the protein C activity, factor V Leiden mutation and the presence of several types of antiphospholipid antibodies in 60 patients with antiphospholipid syndrome. Nineteen patients (31.6%) and 5 controls (8.3%) had decreased protein C activity (95% CI, 10%-37%). 14 patients with high levels of antiphospholipid antibodies and normal factor V molecule (37.8%) and none of the patients with antiphospholipid antibodies in normal ranges and normal factor V molecule had decreased protein C activity (95% CI, 24%-52%; (x 510.4; p 5 0.001). Leiden mutation was found in 5 controls (8.3%) and in 4 patients (8.3%; 95% CI, 8-24%). We found a strong association between decreased protein C activity and presence of anticardiolipin antibodies and antibodies against b2-glycoprotein I. The decreased protein C activity depended on the antibody titre. Although abnormalities of the natural anticoagulant proteins like protein C and protein S seem to be involved in the pathogenesis of the APS, activation of protein C also occurs during the process of clotting. Studies such as we describe may help us identify subsets of patients whose clotting is dependent on protein C-antiphospholipid interactions that may lead to future novel therapies.
Boyanovski
B
B
Clinical Center of Allergology, State University Hospital, Sofia, Bulgaria; Department of Chemistry and Biochemistry, State University Hospital, Sofia, Bulgaria; Department of Clinical Laboratory and Clinical Immunology, State University Hospital, Sofia, Bulgaria; Clinic of Rheumatology, State University Hospital, Sofia, Bulgaria; Department of Dermatology and Venerology, State University Hospital, Sofia, Bulgaria.
Russeva
M
M
Dobreva
G
G
Ganev
V
V
Mladenova
A
A
Peicheva
V
V
Nikolov
K
K
Baleva
M
M