Inducible platelet adherence to human umbilical vein endothelium by anticardiolipin antibody-positive sera.
OBJECTIVE
Our purpose was to determine whether anticardiolipin antibody-positive sera alter platelet adherence to vascular endothelium by a platelet activating factor-dependent mechanism.


METHODS
Anticardiolipin antibody-positive sera were used in an in vitro platelet-endothelial adherence assay. Confluent endothelial monolayers were randomly assigned for exposure to a 20% concentration of experimental and control sera. Platelets were radiolabeled with chromium 51, and adherence was assessed by quantification of endothelium-associated gamma emission.


RESULTS
Inducible platelet adherence was observed by endothelial cell preincubation with sera from anticardiolipin antibody-positive donors compared with anticardiolipin antibody-negative control experiments (n = 12, platelet adherence 6.4% +/- 1.3% vs 4.5% +/- 1.1%, respectively; p = 0.02). Compared with endothelial cell incubations alone, coincubation of platelets with anticardiolipin antibody-positive sera consistently augmented primary adherence (n = 6, p = 0.042). Furthermore, platelet-adherence induced by antibody-positive sera was consistently attenuated by specific platelet-activating factor antagonists in a dose-dependent fashion (p < 0.001) and was restored by exogenously administered platelet-activating factor.


CONCLUSIONS
Anticardiolipin antibody-induced platelet adherence may constitute an important prerequisite for vascular thrombosis in antibody-positive patients. The findings from this in vitro model suggest direct involvement of platelet-activating factor in this process.
Silver
R K
RK
Department of Obstetrics and Gynecology, Evanston Hospital, Northwestern University Medical School, IL 60201, USA.
Mullen
T A
TA
Caplan
M S
MS
O'Connell
P D
PD
Ragin
A
A
D017153:Antibodies, Anticardiolipin / Q000494:pharmacology*; D001381:Azepines / Q000494:pharmacology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology*; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology*; D010973:Platelet Adhesiveness; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011897:Random Allocation; D014230:Triazoles / Q000494:pharmacology; D014471:Umbilical Veins
D017153:Antibodies, Anticardiolipin; D001381:Azepines; D007106:Immune Sera; D010975:Platelet Aggregation Inhibitors; D014230:Triazoles; C052518:WEB 2086