Inhibition of thrombin-induced platelet aggregation using human single-chain Fv antibodies specific for TREM-like transcript-1.
TREM-like transcript-1 (TLT-1) is a novel platelet membrane receptor, which has been recently characterized in mice. TLT-1 is expressed exclusively in platelets and megakaryocytes, and its expression is dramatically upregulated upon platelet activation, suggesting that it plays a unique role in hemostasis and/or thrombosis. In this study we identified and characterized highly specific human monoclonal antibodies that bind to TLT-1 by screening a naïve library of single chain Fv fragments (scFvs) displayed on filamentous phage (Thomlinson I library). These scFvs detected plate-bound TLT-1, captured soluble TLT-1, and readily reacted with cell-bound TLT-1 on transfectants and primary human platelets. Most importantly, anti-TLT-1 scFvs inhibited thrombin-mediated human platelet aggregation. This inhibition was specific for thrombin-induced aggregation and was reversible with higher doses of agonist. These data are the first to demonstrate a biological role for TLT-1 and its potential as a therapeutic target. The human scFvs isolated in this study may represent novel anti-platelet therapeutic agents.
Giomarelli
Barbara
B
Molecular Targets Development Program, NCI-Frederick, 560/Rm 31-46, Frederick, MD 21702-1201, USA.
Washington
Valance A
VA
Chisholm
Maia M
MM
Quigley
Laura
L
McMahon
James B
JB
Mori
Toshiyuki
T
McVicar
Daniel W
DW
D000911:Antibodies, Monoclonal / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D000918:Antibody Specificity; D001667:Binding, Competitive; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005343:Fibrinolytic Agents / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D019151:Peptide Library; D010974:Platelet Aggregation / Q000187:drug effects*; D011971:Receptors, Immunologic / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014162:Transfection
D000911:Antibodies, Monoclonal; D005343:Fibrinolytic Agents; D007135:Immunoglobulin Variable Region; D019151:Peptide Library; D011971:Receptors, Immunologic; C473366:TREML1 protein, human; D013917:Thrombin