Abstract
Porcine kidney extracts (PKE) posses colony-promoting activity (CPA) which stimulates primitive hematopoietic cells in the presence of granulocyte/macrophage colony-stimulating factor (GM-CSF), but PKE itself does not stimulate colony formation on murine bone marrow cells.We have compared the CPA of PKE with that of recombinant cytokines or CSFs such as interleukin-1 alpha (IL-1α), IL-3, IL-6, granulocyte colony-stimulating factor (G-CSF), GM-CSF and macrophage colony-stimulating factor (CSF-1). All of these factors were less potent than PKE.Furthermore, the combinations of IL-1α or PKE with G-CSF, GM-CSF, IL-3 or IL-6 were examined in the presence of one of these factors such as CSF. It is found that PKE acts synergistically with G-CSF, GM-CSF, IL-3 and IL-6, showing enhancement ratios of 10, 2.5, 4.2 and 30, respectively. The combination of IL-1α resulted in poor colony formation in contrast with those of PKE, except for CSF-1.These results suggest that the CPA of the factor(s) in PKE differ from the cytokines and CSFs tested in this study, and is significantly affected by various types of CSF.
