TLR-4 surface display on human monocytes is increased in septic patients

Sepsis is a serious condition, most often occurring as a complication of bacterial infections. The Toll-like receptors (TLR)-2 and TLR-4 have been identified as key molecules in response to Gram-positive and Gram-negative bacteria. This study aimed to assess possible alterations of the surface display of TLR-2 and TLR-4 on monocytes and granulocytes derived from patients with sepsis in comparison with healthy controls. -

We have utilized flow-cytometry to determine the presence of TLR-2 and TLR-4 on the cell surface at baseline and in response to LPS (40 ng/ml) in vitro. -

We found no significant differences of TLR-2 display on monocytes and granulocytes from septic patients compared to controls. Surface display of TLR-4 on monocytes from septic patients at baseline was significantly higher than in healthy controls but there was no further response to LPS, whereas controls showed a significant increase of TLR-4 display on the cell surface after LPS stimulation. In contrast, TLR-4 baseline cell surface display on granulocytes was significantly lower in septic patients than in controls and there was no response to LPS in both groups. -

Our data suggest a complex relationship between TLR-4 display and bacterial challenge in vivo and in vitro.