The beta chain of the GPIIb molecule on ruminant leukocytes and platelets is not labelled by the sulfo-NHS-biotin method

Production and characterization of monoclonal antibodies against dog immunoglobulin isotypes

A panel of six monoclonal antibodies (mAbs) recognizing antigenic determinants on canine immunoglobulin (Ig) heavy or light chains was produced and characterized. All monoclonals recognized the IgG(2) subclass, although only two were subclass-specific (CA3H1 and CA4F1). The CA3B8 mAb was found to be specific for an epitope on canine immunoglobulin G heavy chain, (IgG(1) and IgG(2) subclasses). Two mAbs (CA2E9 and CA5B2) reacted with an epitope on the heavy chain of canine IgG and IgM and another, CA4E7, bound to canine IgA, IgG and IgM isotypes; CA4E7 recognized an epitope on canine immunoglobulin light chain. CA4E7, CA4F1 and CA5B2 recognized an epitope in the Fab region. Three mAbs, CA3B8, CA4E7 and CA5B2, showed much lower reactivity with canine IgG by ELISA when IgG was periodate-treated, suggesting that they recognized a carbohydrate determinant. Cross-reactivity analysis of these mAbs with sera from horse, goat, cow, sheep, pig, cat, rabbit, hamster, rat, mouse and human indicated that two mAbs, CA3B8 and CA5B2, recognized a canine IgG-specific epitope; two others, CA3H1 and CA4E7, recognized an epitope also present in rabbit and sheep immunoglobulin respectively; and the remaining two (CA2E9 and CA4F1) recognized an epitope broadly present on the Igs of the species analyzed. This panel of antibodies will be a useful tool for future canine immunodiagnosis tests. With the exception of CA2E9, all mAbs were able to recognize plasma cells on paraffin-embedded tissues, and will thus be useful for immunohistochemical assays.

Neutrophil-platelet interactions and their relevance to bovine respiratory disease

Respiratory disease is a serious and significant health problem for the bovine industry. Classically, the clinical and research focus has been on the putative causative agents and conditions, and their interactions with host inflammatory cells, particularly alveolar macrophages and blood neutrophils. There is, currently, growing acceptance of the concept that blood platelets play a primary role in the inflammatory process. This review explores the implications of such pro-inflammatory activity, especially in the context of neutrophil-platelet interactions, and the species specificity of cellular responses. The relevance of these issues for the treatment and prevention of bovine respiratory disease is also discussed.

Characterization of the porcine homologue to human platelet glycoprotein IIb-IIIa (CD41/CD61) by a monoclonal antibody

Human gpIIb-IIIa or CD41/CD61 is a Ca(2+)-complex dependent heterodimer, abundant on platelets, that plays a key role in hemostasis. This report describes a murine monoclonal antibody, JM2E5, able to recognize and immunoprecipitate the gpIIb/IIIa surface glycoprotein from porcine platelets. Immunoprecipitation analysis showed an antigen molecular weight of 115 and 85 kDa under nonreducing conditions, and of 110, 100 and 25 kDa under reducing conditions. Immunohistochemistry analyses of frozen sections from several porcine lymphoid organs gave specific staining on platelets. EDTA treated platelets were studied by flow cytometry indicating that the epitope recognized was Ca(2+)-complex independent. Western-blotting experiments with porcine platelet extracts gave an antigen molecular weight of 85 kDa under nonreducing conditions, thus localizing the epitope recognized by JM2E5 on the complex light chain gpIIIa or CD61. JM2E5 was also cross-reacting with human, bovine and horse platelets, as shown by flow cytometry. This mAb would allow further studies on this important adhesion molecule on horses, ruminants and pigs, and it should be especially useful as a general anti-porcine platelet reagent.

Biochemical characterization of antigens detected with anti-platelet monoclonal antibodies

A panel of 18 monoclonal antibodies (mAbs) defined by the third workshop as specific for platelets, clustered in three preliminary groups: PC7, PC13 and PC27. These mAbs were further analysed by immunoprecipitation using extracts of iodinated and biotinylated peripheral blood mononucleated cells (PBMC) and platelets. We could confirm the existence of mAbs with specificities to WC9 (in PC7) and CD41/61 (in PC13). Two mAbs formed a new cluster, WC13, which may be homologous to human CD31 (in PC27). The influence of EDTA and thrombin on the expression of the different antigens on the platelet membrane was assessed by flow cytometry (FCM) analysis, as well as cross-reactivity with platelets from different species.