Conclusion
Thrombotic complications among SLE patients were closely associated with aCL/β2GPI or aPS/PT, with higher prevalence in patients with both antibodies. Addition of aPLs(+)-IgG to the APC sensitivity ratio assay led to significant suppression of the anticoagulant activity of APC. The suppression was more pronounced in double-positive cases. TF expression on monocytes and concentration of TNF-α in culture medium were increased by aPLs, again more pronounced in double-positive cases. These results indicate that the effects of aCL/β2GPI and aPS/PT are synergic both for APC anticoagulant activity and for production of TF and TNF-α from mononuclear cells. These modes of thrombogenic action of aPLs could be an important target for developing specific measures to prevent complications of SLE.
Methods
We enrolled 97 SLE patients and 38 healthy control volunteers and performed activated protein C (APC) resistance screening test using their plasma samples. To detect the direct effect of aPLs IgG on APC, we developed an APC sensitivity ratio assay. Effects of aPLs IgG on monocytes were studied by measuring the surface expression of tissue factor (TF) and excretion of TNF-α from peripheral blood mononuclear cell culture.