Lipopolysaccharide priming of superoxide release by human neutrophils: role of membrane CD14 and serum LPS binding protein.

Previous studies have suggested that lipopolysaccharide (LPS) interactions with neutrophils and monocytes are mediated via the CD14 receptor, in the presence of serum factors such as LPS-binding protein (LBP) and septin. The present study was designed to test if CD14-mediated LPS priming of human neutrophils is dependent upon the presence of serum proteins and to evaluate the contribution of serum factors in LPS-neutrophil interactions. The results demonstrate that CD14 mediates the priming of neutrophil superoxide release by LPS both in the presence and in the absence of serum. However, priming by LPS is greatly enhanced in the presence of human serum, and the factor responsible for this phenomenon is LBP and not heat-sensitive proteins, such as septin.