Human cord blood conditioned medium enhances leukemia colony formation in vitro

Childhood T-cell acute lymphoblastic leukemia (T-ALL) is one of the most co mmon childhood cancers. Recently, we observed that pre-conditioning sub-let hally irradiated immunodeficient mice with human cord blood mononuclear cel ls facilitates in these mice high level engraftment of primary T-ALL cells obtained from patients. Here we report that human cord blood cells secrete a factor(s) which markedly enhances in vitro both colony number and burst s ize of the T-ALL clonogenic progenitors from patients. The enhancing activi ty does not correspond to IL-2, IL-15, nor to several other cytokines impli cated in T cell proliferation/activation. Thus, it is possible cord blood m ay secrete an as yet unidentified factor(s) acting on leukemia clonogenic p rogenitors of T-ALL. Collectively, these studies should prove invaluable in addressing the growth properties of primary T-ALL cells from patients. (C) 2000 Elsevier Science Ltd. All rights reserved.