Title: Human platelet aggregation by murine monoclonal antiplatelet antibodies is subtype-dependent
Authors: De Reys, S ×
Blom, C
Lepoudre, B
Declerck, Paul
De Ley, Marc
Vermylen, Jozef
Deckmyn, Hans #
Issue Date: May-1993
Series Title: Blood vol:81 issue:7 pages:1792-800
Abstract: Twenty murine monoclonal antibodies (MoAbs) generated against different human platelet antigens induced clumping of human platelets in plasma and buffer. Whereas one MoAb could agglutinate platelets, clumping for 19 MoAbs was blocked by metabolic inhibitors, indicating that these induce platelet activation. Fifteen MoAbs were of IgG1, two of IgG2a, and two of IgG2b subtype. F(ab')2 fragments of these did not evoke an aggregatory response, but specifically inhibited aggregations by and binding of their respective intact MoAbs to platelets. Single-platelet counting technology indicated that the MoAbs bind through their antigen-binding and Fc domains mainly to the surface of the same platelet, rather than cause interplatelet-binding. Despite these similarities, the mechanism of action was nevertheless subtype-dependent. Aggregation induced by all IgG1 antibodies could consistently be prevented by blocking the Fc gamma II-receptor, whereas aggregations induced by all IgG2 antibodies still occurred with blocked Fc-receptor, provided functional complement was present. We therefore conclude that platelet activation by MoAb-binding is initiated by antigen recognition followed by an Fc domain-dependent step, which involves the Fc gamma II-receptor for IgG1-type MoAbs and complement-binding for IgG2-type MoAbs. Thus, antibodies of different subtypes can aggregate platelets via different pathways.
ISSN: 0006-4971
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Biochemistry, Molecular and Structural Biology Section
Molecular and Vascular Biology
Laboratory for Pharmaceutical Biology (-)
Chemistry, Campus Kulak Kortrijk
Interdisciplinary Research Facility Life Sciences, Campus Kulak Kortrijk
Faculty of Medicine - miscellaneous
× corresponding author
# (joint) last author

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