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 leuk emia (AML) blasts with allogeneic platelets enhances blast proliferation an d constitutive cytokine secretion. In the present study the effects of AML blasts on the platelet release of soluble mediators are characterized. Norm al platelets released soluble (s) P-selectin and platelet-derived growth fa ctor (PDGF), both when cultured alone and in the presence of AML blasts, an d for certain patients the presence of AML blasts increased the platelet re lease of these mediators. Addition of exogenous interleukin (IL) 10 to plat elet-AML blast cultures further increased platelet release of PDGF and sP-s electin, For certain patients decreased AML blast cytokine secretion was ob served when PDGF-specific antibodies were added to cultures with blasts plu s platelets, these results indicate that platelet release of PDGF is a mole cular mechanism for the enhancement of AML blast cytokine secretion. We con clude that complex functional alterations are induced both in AML blasts an d normal allogeneic platelets during in vitro co-culture of leukemia cells and platelets.