Studies of microparticles in patients with the antiphospholipid syndrome (APS).
OBJECTIVE
To study circulating platelet, monocyte and endothelial microparticles (PMPs, MMPs and EMPs) in patients with antiphospholipid syndrome (APS) in comparison with healthy controls.


METHODS
Fifty-two patients with APS and 52 healthy controls were investigated. MPs were measured on a flow cytometer (Beckman Gallios) and defined as particles sized < 1.0 µm, negative to phalloidin, positive to lactadherin and positive to either CD42a (PMPs), CD144 (EMPs) or CD14 (MMPs). Exposure of CD142 (TF) was measured on CD144 positive MPs.


RESULTS
Total number of MPs (i.e. lactadherin positive particles) was higher in APS patients versus controls (p < 0.001). An increased number of EMPs (p < 0.001), increased TF-positive EMPs (p < 0.001) and increased MMPs (p < 0.001) were also observed. PMP numbers did not differ between the groups. None of the MP types differed in numbers between obstetric and thrombotic APS patients.


CONCLUSIONS
We observed a high number of EMPs expressing TF in APS patients. The numbers of MMPs and total EMPs were also higher as compared with healthy controls but in contrast to previous reports, the number of PMPs did not differ between groups.
Karolinska Institutet, Department of Medicine Solna, Unit of Rheumatology, Karolinska University Hospital, Stockholm, Sweden. anna.vikerfors@karolinska.se
A
A
Vikerfors
F
F
Mobarrez
K
K
Bremme
M
M
Holmström
A
A
Ågren
A
A
Eelde
M
M
Bruzelius
A
A
Antovic
H
H
Wallén
E
E
Svenungsson
D000328:Adult; D016736:Antiphospholipid Syndrome / Q000097:blood* / Q000150:complications; D016022:Case-Control Studies; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011248:Pregnancy Complications / Q000209:etiology; D013927:Thrombosis / Q000209:etiology