Effects of acute myelogenous leukemia blasts on platelet release of soluble P-selectin and platelet-derived growth factor

Complex interactions occur between platelets and normal as well as leukemic myeloid cells. In vitro co-culture of platelets and acute myelogenous leukemia (AML) blasts with allogeneic platelets enhances blast proliferation and constitutive cytokine secretion. In the present study the effects of AML blasts on the platelet release of soluble mediators are characterized. Normal platelets released soluble (s) P-selectin and platelet-derived growth factor (PDGF), both when cultured alone and in the presence of AML blasts, and for certain patients the presence of AML blasts increased the platelet release of these mediators. Addition of exogenous interleukin (IL) 10 to platelet-AML blast cultures further increased platelet release of PDGF and sP-selectin. For certain patients decreased AML blast cytokine secretion was observed when PDGF-specific antibodies were added to cultures with blasts plus platelets, these results indicate that platelet release of PDGF is a molecular mechanism for the enhancement of AML blast cytokine secretion. We conclude that complex functional alterations are induced both in AML blasts and normal allogeneic platelets during in vitro co-culture of leukemia cells and platelets.