DEMONSTRATION OF FELINE AND CANINE PLATELET GLYCOPROTEINS BY IMMUNOCHEMISTRY AND LECTIN HISTOCHEMISTRY

Canine and feline platelet cytocentrifuge preparations (CCPs), cryosta t and paraffin-embedded bone marrow sections were used in this study. We evaluated whether platelets, megakaryocytes and megakaryocyte precu rsor cells could be labelled by monoclonal antibodies (Y2/51, CLB-thro mb/1, HPL1) against human platelet membrane glycoprotein GP IIIa and t he GP IIb/IIIa complex or by the following 10 biotinylated lectins: co ncanavalin A (Con A), Lens culinaris agglutinin (LCA), Pisum sativum a gglutinin (PsA), wheat germ agglutinin (WGA), peanut agglutinin (PNA), Phaseolus vulgaris lectin (PHA-L), Ricinus communis agglutinin 120 (R CA120), Ulex europaeus agglutinin - I(UEA-1), soybean agglutinin (SBA) and Dolichos biflorus agglutinin (DBA). Monoclonal antibodies Y2/51 a nd HPL1 cross reacted with platelets and megakaryocytic cells from bot h species, whereas CLB-thromb/1 was unreactive with canine preparation s. Only Y2/51 labelled megakaryocytic cells in paraffin-embedded sampl es. LCA, PSA, WGA and PHA-L labelled feline and canine platelets and d ifferent numbers of morphologically identifiable megakaryocytes and nu merous other, mostly myeloid, cells. Immunoblots of dog and cat platel et lysates using Y2/51 visualized a single protein of 95 kDa (unreduce d), a mol .wt value within the range of those reported for GP IIIa. So me of the platelet (but not necessarily megakaryocyte) glycoproteins r eacting with LCA, PSA and WGA could be identified in lectin blots foll owing one- or two (nonreduced/reduced)-dimensional sodium dodecyl sulp hate-polyacrylamide gel electrophoresis (SDS-PAGE). Thus in dogs and c ats, the immunohistochemical detection of GP IIIa (and eventually GP I Ib/IIIa) rather than lectin binding patterns could be important for th e diagnosis of megakaryoblastic leukaemias.