Phospholipid binding of antiphospholipid antibodies and placental anticoagulant protein.
We evaluated the interaction of antiphospholipid antibodies (aPL) with placental anticoagulant protein I (PAP I), a calcium-dependent phospholipid binding protein which may act as a natural anticoagulant. Clotting assays showed additive prolongation of clotting times with aPL and PAP I. ELISA and vesicle phospholipid binding studies showed PAP I inhibition of aPL binding to phospholipid but no inhibition of PAP I-phospholipid binding by aPL. aPL and PAP I interact additively in anticoagulant activity in in vitro clotting systems and compete for phospholipid in ELISA system. These data support the hypotheses that aPL and PAP I may recognize similar phospholipid epitopes and that in vivo interaction may occur.
Division of Rheumatic Diseases, Hospital for Special Surgery-Cornell University Medical Center, New York, New York 10021.
L R
LR
Sammaritano
A E
AE
Gharavi
C
C
Soberano
R A
RA
Levy
M D
MD
Lockshin
D017302:Annexins; D000906:Antibodies / Q000276:immunology*; D001777:Blood Coagulation / Q000276:immunology*; D001780:Blood Coagulation Tests; D002122:Calcium Chloride / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D066298:In Vitro Techniques; D010743:Phospholipids / Q000276:immunology*; D010920:Placenta / Q000276:immunology; D011257:Pregnancy Proteins / Q000276:immunology* / Q000302:isolation & purification
D017302:Annexins; D000906:Antibodies; D000939:Epitopes; D007074:Immunoglobulin G; D010743:Phospholipids; D011257:Pregnancy Proteins; D002122:Calcium Chloride