Monocytes as a site of production of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) in the septic host.

The role of blood monocytes in the secretion of soluble triggering receptor expressed on myeloiod cells (sTREM-1) was studied in 90 patients with septic syndrome due to ventilator-associated pneumonia. Blood monocytes were isolated on 7 consecutive d after initiation of symptoms. Monocytes were incubated in the absence or presence of LPS and concentrations of sTREM-1 and TNFalpha in cell supernatants and serum were estimated by an enzyme-immunoassay. sTREM-1 and TNFalpha were consistently present at detectable levels in the cell supernatants. LPS induced increased levels of TNFalpha but not of sTREM-1. Supernatants recovered from monocytes on d 1 showed levels of sTREM-1 higher than those recovered on any of the following 6 d (p<0.05); these levels were higher in non-survivors than in survivors. Supernatants recovered from monocytes on d 1 of patients with severe sepsis had elevated concentrations of sTREM-1 compared to patients with septic shock and similar to patients with sepsis. A negative correlation was found between levels of sTREM-1 in the cell supernatants and the percentage of apoptotic monocytes. In essence, the above results suggest that monocytes contribute to the production of sTREM-1 in the event of septic syndrome.