title: Effects of antiphospholipid antibodies on in vitro platelet aggregation.
abstract: Antiphospholipid antibodies contribute to the development of thrombosis, although precise mechanisms remain to be elucidated. We determined the effects of affinity-purified anti-beta(2)-glycoprotein 1 (anti-β(2)GP1) and anti-prothrombin (anti-PT) antibodies on in vitro platelet aggregation. Adenosine diphosphate (ADP) and collagen-induced platelet aggregation were performed using platelet-rich plasma ([PRP] 250 × 10(9)/L). Antiphospholipid antibodies (1.25-10 μg/mL) were preincubated with PRP for 10 minutes at 37°C prior to the addition of agonist. Anti-β(2)GP1 antibodies significantly reduced platelet aggregation (percentage area under the curve; %AUC) in a concentration-dependent manner using both 5 μmol/L (P < .001) and 2.5 μmol/L (P = .038) ADP but did not significantly affect the rate of aggregation. Anti-PT antibodies significantly enhanced 5 µg/mL collagen-induced platelet aggregation (%AUC; P = .034) but did not affect ADP-induced platelet aggregation. These results suggest (1) interactions and effects of antiphospholipid antibodies on platelets are agonist and concentration dependent and (2) anti-β(2)GP1 antibodies may inhibit dense granule release and/or inhibition of the arachidonic acid pathway.
authors: School of Human Life Sciences, University of Tasmania, Launceston, Tasmania, Australia.
authors: Anita A
authors: AA
authors: Palatinus
authors: Kiran D K
authors: KD
authors: Ahuja
authors: Murray J
authors: MJ
authors: Adams
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry / Q000494:pharmacology; D017152:Antibodies, Antiphospholipid / Q000097:blood / Q000276:immunology / Q000302:isolation & purification / Q000494:pharmacology*; D001792:Blood Platelets / Q000276:immunology / Q000378:metabolism*; D003094:Collagen / Q000737:chemistry / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects* / Q000276:immunology; D013927:Thrombosis / Q000097:blood / Q000276:immunology
chemical_list: D017152:Antibodies, Antiphospholipid; D000244:Adenosine Diphosphate; D003094:Collagen