Evaluation of glycoprotein Ib expression on feline platelets.
OBJECTIVE
To determine whether platelets obtained from cats expressed glycoprotein Ib (GPIb).


METHODS
Platelets obtained from 11 specific-pathogen-free cats.


METHODS
Platelets were analyzed by use of immunofluorescence microscopy, flow cytometry, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, western immunoblot analysis, and immunoprecipitation.


RESULTS
Immunofluorescence microscopy and flow cytometry revealed the protein on the surface of feline platelets. Biochemical studies (western immunoblot analysis and immunoprecipitation) revealed a 140-kd membrane glycoprotein. Additional biochemical studies revealed that feline GPIb was sensitive to proteolysis, because platelet cytoskeletons prepared with low concentrations of a calpain inhibitor (ie, leupeptin; 100 microg/ml) had substantial proteolysis, and there was an association of protein fragments with the actin cytoskeleton.


CONCLUSIONS
Analysis of these results indicate that feline platelets express a 140-kd membrane protein that is recognized by monoclonal antibodies developed against GPIb. Application of standardized ELISA to quantitate glycocalicin, the water-soluble fragment of GPIb, may provide important information on the production of microvesicles, increased platelet turnover, and abnormal proteolysis.
Tablin
F
F
Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, USA.
Johnsrude
J D
JD
Walker
N J
NJ
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001792:Blood Platelets / Q000378:metabolism*; D002415:Cats / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005434:Flow Cytometry / Q000662:veterinary; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D011233:Precipitin Tests / Q000662:veterinary; D013047:Specific Pathogen-Free Organisms
D000911:Antibodies, Monoclonal; D019038:Platelet Glycoprotein GPIb-IX Complex