CHARACTERIZATION OF A MEMBRANE-RECEPTOR ON RUMINANTS AND EQUINE PLATELETS AND PERIPHERAL-BLOOD LEUKOCYTES SIMILAR TO THE HUMAN INTEGRIN RECEPTOR GLYCOPROTEIN IIB IIIA (CD41/61)/

This paper describes two anti-glycoprotein IIb/IIIa or CD41/61 murine monoclonal antibodies (Co.35E4 and Co.2oA1). The cellular distribution and apparent molecular weight of the antigen detected by these antibo dies is consistent with their reaction with ruminant and equine glycop rotein IIb/IIIa. Biochemical analysis of the equine molecule using sod ium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) rev ealed bands of 24, 100 and 110 kDa under reducing conditions and 115 a nd 80 kDa under nonreducing conditions. Biochemical analysis of rumina nt antigen revealed that the 24 kDa band did not appear owing to the a bsence of labelling with sulpho-NHS-biotin. Co.35E4 and Co.20A1 recogn ised two different Ca2+ complex independent epitopes. The glycoprotein IIb/IIIa was present on ruminant and equine granulocytes, monocytes a nd platelets. However, binding on granulocytes and monocytes was due t o the adsorption of membrane platelet fragments.