Platelet- and endothelial-derived microparticles in the context of different antiphospholipid antibody profiles

Objectives Studies on microparticles (MPs) in patients with antiphospholipid antibodies (aPL) are sparse and inconclusive. The relation between MPs and different aPL antibody profiles has never been tested. We evaluated the presence of platelet and endothelial microparticles in patients positive for IgG anti-beta 2-glycoprotein I (a beta 2GPI) antibodies according to triple, double and single positive aPL profiles. Methods Megamix (Biocytex) was used to set up the MPs gating according to the datasheet. Markers of Platelet Microparticles (PMPs) were CD41a-PE and annexin-V-FITC that was used to determine phosphatidylserine (PS) exposure. CD144-FITC was used as a marker of Endothelial Microparticles (EMPs). Results The number of total MPs and EMPs was significantly higher in triple positive groups with respect to single positive group and showed a significant correlation with IgG a beta 2GPI titers. The number PMPs was the lowest in triple positive group and inversely correlated with IgG a beta 2GPI titers. Conclusions Elevated levels of total MPs and EMPs suggest a state of vascular activation in IgG a beta 2GPI positive individuals according to the number of positive tests. PMPs may be fast cleared from circulation in high risk triple positive patients.

Automated summary

This study investigated microparticles (MPs) in patients with antiphospholipid antibodies (aPL) and found that the levels of total MPs and endothelial microparticles (EMPs) were significantly higher in triple positive patients compared to single positive patients, and were correlated with IgG antibody titers. Additionally, platelet microparticles (PMPs) were found to be the lowest in triple positive patients and inversely correlated with IgG antibody titers.