title: Detection of antiplatelet antibody: comparison of platelet immunofluorescence, agglutination, and immunoinjury tests using rabbit antiequine platelet serum.
abstract: Immunofluorescence, tube agglutination, and platelet factor-3 immunoinjury tests for detecting antiplatelet antibody were compared using a heterologous system of equine platelets and rabbit antiequine platelet serum. Platelet immunofluorescence tests were performed using paratormaldehyde-fixed platelets in suspension as well as in air-dried smears on glass slides (solid phase). Bright homogeneous, membranous, specific fluorescence was seen in both assays with anti-immunoglobulin G (IgG) and protein G fluorescein isothiocynate conjugates (FITC-conjugates). Protein A conjugate gave nonspecific fluorescence irrespective of normal or antiserum treatment. Anti-IgG and protein G conjugates in suspension immunofluorescence tests with the same antiserum yielded antibody titers of 1:1024 and 1:128, respectively. Similarly, respective titers of 1:512 and 1:64 were obtained with solid phase immunoassay. Platelet suspension assay was slightly better than the solid phase assay. These observations indicated that anti-IgG was more sensitive than protein G in detecting antiplatelet antibody by fluorescence microscopy, while protein A was ineffective because of its nonspecificity. Chloroquine treatment of platelets failed to reduce the nonspecific fluorescence. Platelet agglutination and platelet factor-3 tests were relatively less sensitive to detect equine antiplatelet antibody.
authors.affiliation: Department of Clinical Pathology, School of Veterinary Medicine, University of California, Davis, CA 95616.
authors.forename: Nemi C.
authors.initials: NC
authors.lastname: Jain
authors.forename: Ram G.
authors.initials: RG
authors.lastname: Dhawedkar
authors.forename: J. L.
authors.initials: JL
authors.lastname: Vegad
authors.forename: Constance S.
authors.initials: CS
authors.lastname: Kono