Contrast medium attenuates platelet activation and platelet-leukocyte cross-talk

The influence of ionic and non-ionic contrast media (CM) on platelet and leukocyte activation and platelet-leukocyte crosstalk was investigated in hirudinized whole blood. The blood was incubated with and without the ionic CM ioxaglate and the nonionic CM iodixanol at 37 degrees C for 5 min, without or with stirring. Platelet and leukocyte activation and platelet-leukocyte aggregation were measured using whole blood flow cytometry. When blood samples were pre-incubated in the presence of 2%, 5%, and 10% of CM without stirring, both ioxaglate and iodixanol had little effect on unstimulated samples, but dose-independently decreased 1 microM ADP-induced platelet P-selectin expression and fibrinogen binding, and thus platelet-leukocyte aggregate formation. Ioxaglate had little effect on leukocyte CD11b expression, whilst iodixanol slightly enhanced resting and N-formyl-methionyl-leucyl-phenylalanine (fMLP; 0.1 microM)-stimulated leukocyte CD11b expression. Blood samples were also incubated with stirring to investigate the impact of CM (5% of ioxaglate or iodixanol) on platelet-leukocyte cross-talk. Collagen induced marked platelet activation and platelet-leukocyte aggregation, and subsequently elevated leukocyte CD11b expression. The latter was attenuated by ioxaglate and iodixanol, and was accompanied by reduced platelet-leukocyte aggregation. In conclusion, the CM ioxaglate and iodixanol attenuate platelet activation and platelet-leukocyte cross-talk. Inhibitory effects of the contrast agents on this cross-talk are apparently exerted by reducing heterotypic conjugation, and may be beneficial in connection with PCI.