Myelodysplastic syndromes: prognostic significance of multilineage dysplasia in patients with refractory anemia or refractory anemia with ringed sideroblasts

although full irreversible aggregation was impaired.1 But inhibition of full, irreversible aggregation by wortmannin did not impair thromboxane A2 accumulation in response to LIBS6 plus fibrinogen. These data suggest that the close platelet-to-platelet contact that is brought about by platelet aggregation (primary or full) is not sufficient to generate thromboxane A2 and depends on signaling from the ADP receptors. Hence we disagree with the interpretation of Cattaneo et al of the previously published results from several laboratories. We stand by our interpretation of our results that outside-in signaling from both the integrin IIb 3 and the P2 receptors is required for ADP-induced thromboxane A2 generation in platelets. We agree with Cattaneo et al that ADP-induced thromboxane generation is greatly enhanced and can be seen in most healthy individuals when extracellular calcium is decreased to micromolar levels. Jianguo Jin, Todd M. Quinton, Jin Zhang, Susan E. Rittenhouse, and Satya P. Kunapuli