Crossreactivity of human versus swine platelet surface antigens is similar for glycoproteins Ib and IIIa, but not for the glycoprotein IIb/IIIa complex

Swine platelets are very similar to those of humans and are therefore relevant to cardiovascular research. The swine coronary circulation mimics the human circulation and is large enough to obtain multiple blood samples in survival experiments. In swine regional ischemia similar to the human condition is easily obtainable, which makes the porcine model an ideal choice to study coronary artery disease. However, little is known about the similarity between swine and human platelet surface antigens. We tested the hypothesis that certain swine platelet antigens could crossreact with antihuman antibodies. Using FITC conjugated monoclonal murine antihuman platelet antibodies, surface antigen expression was determined for human and Yorkshire swine platelets. Expression of CD9 (p24), CD42B (Ib), CD41b (IIb), CD61 (IIIa), CD41a (IIb/IIIa), CD49b (VLA-2), CD62p, (P selectin), CD31 (PECAM-1), and CD51/CD61 (vitronectin) was measured by flow cytometry. Significant crossreactivity with human platelets was observed consistently for swine platelet GP Ib and GP IIIa. Crossreactivity of the swine GPIb and GP IIIa with the human receptors is evidence of receptor similarity between human and swine platelets. The implications of significant crossreactivity of these antigens and the lack of recognition of IIb/IIIa needs to be understood in cardiovascular research. Determining commercially available antihuman GP Ib and GP IIIa, rather than GP IIb/IIIa, would contribute to better elucidation of the effects of von Willebrand factor and the booming family of platelet inhibitors in the swine model of ischemia-reperfusion.