Contamination of human placental granulocyte macrophage colony stimulating factor by bacterial endotoxin: its removal by a simple adsorption technique.

Bacterial endotoxin was detected by the Limulus Amebocyte Lysate (LAL) assay in four preparations of human placental granulocyte-macrophage colony-stimulating-factor (HP-CSF), a humoral factor required for the production of human granulocyte-macrophage colonies in semi-solid cultures. The complete removal of endotoxin from these preparations was carried out by its adsorption to LAL proteins, either directly of following coupling to sepharose beads. Removal of endotoxin from HP-CSF did not result in any reduction of its in vitro granulopoietic activity, and the LAL-sepharose complex could be recycled for further use.