The effect of the protein-bound polysaccharide extracted from Glaciecola polaris (PSG) was investigated in vitro in the protection of oxidatively-injured mouse macrophages stressed by tert-butyl hydroperoxide (tbOOH) or by oxidatively modified low-density lipoprotein (Ox-LDL). The results showed that PSG treatments to protect the macrophages from oxidative injury was effective and the macrophage colony-stimulating factor (M-CSF) exhibited some similar effects. It was speculated that both M-CSF and PSG could protect macrophages from oxidative injury. The results suggested that the effects of PSG were associated with its capability of inducing M-CSF expression. (c) 2005 Elsevier Ltd. All rights reserved.