Lipopolysaccharide primes human basophils for enhanced mediator release: requirement for plasma co-factor and CD14.

Lipopolysaccharide (LPS) is known to enhance IgE-mediated basophil degranulation. Recently, the complex of LPS and plasma LPS-binding protein(LBP) has been shown to induce secretory response via CD14 in monocytes and neutrophils. In the current study, we observed that the sensitivity to LPS of basophils was increased to 100-fold by co-incubation with plasma. LPS promptly completed its effect and amplified degranulation by stimuli bypassing IgE-receptors. Treatment with anti-CD14 completely abolished the priming effect of LPS. These results indicate that the priming effect of LPS on basophil mediator release is mediated via CD14, and that plasma co-factor, possibly identical to LBP, potentiates this reaction.