Platelet functions and clinical effects in acute myelogenous leukemia

Platelets interact with normal peripheral blood cells via adhesion as well as soluble mediators, and platelet released mediators can affect hematopoietic stem and progenitor cells. Interactions may also be involved between platelets and circulating malignant cells, which is suggested by the effects platelets seem to have on metastasis and the various platelet abnormalities observed in various malignant disorders, including acute myelogenous leukemia (AML) and other leukemias. It is only recently that the interactions between platelets and AML cells have been characterized in detail, and studies show that; i) platelets and AML blasts can affect functional characteristic of each other, ii) chemotherapeutic drugs frequently used in AML therapy can alter several platelet functions, iii) the systemic levels of various cytokines are enhanced during AML chemotherapy, including cytokines known to affect both leukemic blasts and platelet activation, and iv) platelet secretion of growth factors are clearly detected in peripheral blood stem cells autografts. In this review we describe platelet interactions with normal leukocytes, normal hematopoietic and leukemic cells and the possible clinical relevance of these interactions in AML.