Interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) enhance lipopolysaccharide binding to neutrophils via CD14.

OBJECTIVE

Lipopolysaccharide (LPS), a potent and pleiotropic stimulator of immune cells, binds to neutrophils via CD14, but less densely than to monocytes. The present study was designed to investigate whether cytokines modulate LPS binding to neutrophils via CD14.

METHODS

Neutrophils were cultured with LPS after pretreatment with cytokines, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 alpha (IL-1alpha), or granulocyte-colony stimulating factor (G-CSF). Binding of LPS and CD14 expression on neutrophils were analyzed by flow cytometry, using anti-LPS and anti-CD14 monoclonal antibodies (mAb).

RESULTS

LPS alone showed only slight binding to neutrophils, but pretreatment with IFN-gamma or TNF-alpha before LPS exposure markedly increased LPS binding and CD14 expression on the surfaces of neutrophils. The dramatic increase in LPS binding was not seen with IL-1alpha or G-CSF. Anti-CD14 blocking mAb completely inhibited the binding effect.

CONCLUSIONS

These results demonstrate that IFN-gamma and TNF-alpha enhance LPS binding to neutrophils via CD14, suggesting that the priming effect of cytokines on neutrophils is important for LPS binding.