The Role of Interleukin-1 and Granulocyte-Macrophage Colony-Stimulating Factor in the Paracrine Stimulation of an In Vivo-Derived Murine Myeloid Leukemia

WEHI-274.3 is a cell line isolated from an in vivo-derived, murine myelomonocytic leukemia. Although the survival and growth of WEHI-274.3 cells in vitro is absolutely dependent on the addition of exogenous growth factors such as interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), or colony-stimulating factor-I, when injected into syngeneic mice the cell line is tumorigenic. Sera from normal mice contain low levels of an activity that sustains survival of WEHI-274.3 but does not stimulate growth. In contrast, sera from mice bearing the WEHI-274.3 leukemia contained levels of CSF-1 and GM-CSF that stimulated the growth of WEHI-274.3 cells. Supernatants of cultures of WEHI-274.3 cells contained an activity that stimulated 3T3 fibroblasts to release an activity that stimulated the growth