Highly potent anti-human GPVI monoclonal antibodies derived from GPVI knockout mouse immunization.
Recent progress in the understanding of thrombus formation has suggested an important role for glycoprotein (GP) VI in this process. To clarify the exact role in detail, it is necessary to use specific, high affinity inhibitory antibodies. However, possibly due to the conserved structure of GPVI among species, it has been difficult to obtain potent antibodies. In this study, we developed highly potent anti-human GPVI monoclonal antibodies using GPVI knockout mice for immunization. Fab fragments of these antibodies, named OM1 and OM2, potently inhibit collagen-induced platelet aggregation. The IC(50) values for OM1 and OM2 are 0.6+/-0.05 and 1.7+/-0.5 microg/mL, respectively, showing potency greater than, or equal to that of abciximab (1.7+/-0.3 microg/mL), an anti-GPIIb/IIIa antibody. Fab fragments of OM1 and OM2 also potently inhibit collagen-induced ATP release, thromboxane A(2) formation, and platelet adhesion to immobilized collagen under static and flow conditions. Interestingly, platelet aggregation induced with collagen-related peptide was potently inhibited by OM2 but not OM1, indicating that OM1 recognizes an epitope that is different from collagen-related peptide-binding site on GPVI. These results suggest that OM1 and OM2 may be useful tools to understand the role of GPVI in thrombus formation. Furthermore, these antibodies have the potential to be developed as a new class of therapeutic tool.
Otsuka Maryland Medicinal Laboratories, 9900 Medical Center Drive, Rockville, MD 20850, USA.
Yutaka
Y
Matsumoto
Hisao
H
Takizawa
Xiaoqi
X
Gong
Sang
S
Le
Simon
S
Lockyer
Keiji
K
Okuyama
Michinori
M
Tanaka
Masuhiro
M
Yoshitake
Narendra N
NN
Tandon
Junichi
J
Kambayashi
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D000918:Antibody Specificity / Q000276:immunology; D001792:Blood Platelets / Q000166:cytology / Q000378:metabolism; D019556:COS Cells; D002522:Chlorocebus aethiops; D006801:Humans; D007114:Immunization; D007140:Immunoglobulin Fab Fragments / Q000276:immunology / Q000494:pharmacology*; D051379:Mice; D018345:Mice, Knockout; D010973:Platelet Adhesiveness / Q000187:drug effects* / Q000276:immunology; D010974:Platelet Aggregation / Q000187:drug effects* / Q000276:immunology; D010980:Platelet Membrane Glycoproteins / Q000172:deficiency / Q000276:immunology*
D000911:Antibodies, Monoclonal; D007140:Immunoglobulin Fab Fragments; D010980:Platelet Membrane Glycoproteins; C098341:platelet membrane glycoprotein VI