title: Significant reduction in the binding of a monoclonal antibody (LYP 18) directed against the IIb/IIIa glycoprotein complex to platelets of patients having undergone extracorporeal circulation.
abstract: Extracorporeal circulation (ECC) used in open heart surgery gives rise to several hemostatic defects. This work investigates the effect of ECC on patient platelets membrane glycoproteins IIb/IIIa. A monoclonal antibody (LYP 18) directed against the IIb/IIIa complex was used on patient platelets in binding and flow cytometry studies, before and at the end of ECC. An antithrombospondin (LYP 8) monoclonal antibody and a monoclonal antibody (LYP 7) directed against an alpha-granule glycoprotein of 136 kdaltons, present on the platelet surface after secretion, were used in binding studies together with electron microscopy to assess the release of alpha-granules. Results obtained in 7 patients show a significant reduction (p less than 0.02) in the number of LYP 18 monoclonal antibody binding to platelets having undergone ECC (n = 49,725 +/- 16,275) compared to platelets drawn before ECC (n = 72,671 +/- 13,302). Flow cytometry studies indicate a decrease (p less than 0.02) in the percentage of platelets bearing the LYP 18 determinant following ECC (75 +/- 12% vs 66 +/- 14%). Binding of monoclonal antibodies LYP 8 and LYP 7 and electron microscopy studies of patient platelets having undergone ECC do not show degranulation. These results suggest possible cleavage of the IIb/IIIa complex following ECC but no release of alpha-granules.
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D001666:Binding Sites, Antibody; D001792:Blood Platelets / Q000502:physiology*; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D005112:Extracorporeal Circulation; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D008297:Male; D008875:Middle Aged; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins / Q000276:immunology / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D019007:P-Selectin; D010980:Platelet Membrane Glycoproteins