title: Complex formation with nucleic acids and aptamers alters the antigenic properties of platelet factor 4.
abstract: The tight electrostatic binding of the chemokine platelet factor 4 (PF4) to polyanions induces heparin-induced thrombocytopenia, a prothrombotic adverse drug reaction caused by immunoglobulin G directed against PF4/polyanion complexes. This study demonstrates that nucleic acids, including aptamers, also bind to PF4 and enhance PF4 binding to platelets. Systematic assessment of RNA and DNA constructs, as well as 4 aptamers of different lengths and secondary structures, revealed that increasing length and double-stranded segments of nucleic acids augment complex formation with PF4, while single nucleotides or single-stranded polyA or polyC constructs do not. Aptamers were shown by circular dichroism spectroscopy to induce structural changes in PF4 that resemble those induced by heparin. Moreover, heparin-induced anti-human-PF4/heparin antibodies cross-reacted with human PF4/nucleic acid and PF4/aptamer complexes, as shown by an enzyme immunoassay and a functional platelet activation assay. Finally, administration of PF4/44mer-DNA protein C aptamer complexes in mice induced anti-PF4/aptamer antibodies, which cross-reacted with murine PF4/heparin complexes. These data indicate that the formation of anti-PF4/heparin antibodies in postoperative patients may be augmented by PF4/nucleic acid complexes. Moreover, administration of therapeutic aptamers has the potential to induce anti-PF4/polyanion antibodies and a prothrombotic diathesis.
authors.affiliation: Institut für Immunologie und Transfusionsmedizin, Ernst-Moritz-Arndt-Universität, Greifswald, Germany.
authors.forename: Miriam E
authors.initials: ME
authors.lastname: Jaax
authors.forename: Krystin
authors.initials: K
authors.lastname: Krauel
authors.forename: Thomas
authors.initials: T
authors.lastname: Marschall
authors.forename: Sven
authors.initials: S
authors.lastname: Brandt
authors.forename: Julia
authors.initials: J
authors.lastname: Gansler
authors.forename: Birgitt
authors.initials: B
authors.lastname: Fürll
authors.forename: Bettina
authors.initials: B
authors.lastname: Appel
authors.forename: Silvia
authors.initials: S
authors.lastname: Fischer
authors.forename: Stephan
authors.initials: S
authors.lastname: Block
authors.forename: Christiane A
authors.initials: CA
authors.lastname: Helm
authors.forename: Sabine
authors.initials: S
authors.lastname: Müller
authors.forename: Klaus T
authors.initials: KT
authors.lastname: Preissner
authors.forename: Andreas
authors.initials: A
authors.lastname: Greinacher
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000378:metabolism; D052157:Aptamers, Nucleotide / Q000737:chemistry / Q000378:metabolism*; D020029:Base Pairing; D001483:Base Sequence; D001792:Blood Platelets / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D046911:Macromolecular Substances / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009696:Nucleic Acids / Q000737:chemistry / Q000378:metabolism*; D015539:Platelet Activation / Q000276:immunology; D010978:Platelet Factor 4 / Q000276:immunology* / Q000378:metabolism*; D000071228:Polyelectrolytes; D011108:Polymers; D011485:Protein Binding / Q000187:drug effects; D012313:RNA / Q000737:chemistry / Q000378:metabolism
chemical_list: D000906:Antibodies; D052157:Aptamers, Nucleotide; D004247:DNA; D006493:Heparin; D046911:Macromolecular Substances; D009696:Nucleic Acids; D010978:Platelet Factor 4; D000071228:Polyelectrolytes; D011108:Polymers; D012313:RNA