Characterisation 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 antibodies is consistent with their reaction with ruminant and equine glycoprotein IIb/IIIa. Biochemical analysis of the equine molecule using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) revealed bands of 24, 100 and 110 kDa under reducing conditions and 115 and 80 kDa under nonreducing conditions. Biochemical analysis of ruminant antigen revealed that the 24 kDa band did not appear owing to the absence of labelling with sulpho-NHS-biotin. Co.35E4 and Co.20A1 recognised two different Ca2+ complex independent epitopes. The glycoprotein IIb/IIIa was present on ruminant and equine granulocytes, monocytes and platelets. However, binding on granulocytes and monocytes was due to the adsorption of membrane platelet fragments.