For the measurement of sTREM-1, mTREM-1, nTREM-1 and CRP 10 ml of peripheral venous blood were sampled after venipuncture of the antecubitul vein under sterile conditions on the day of admission and on days 3 and 7 of hospitalization. Seven ml were centrifuged and serum was stored in -80°C until assayed for sTREM-1. Three ml were collected into EDTA-coated tubes (Vacutainer, BD) for estimation of nTREM-1 and mTREM-1 expression. Briefly, red blood cells were lysed by ammonium chloride. White blood cells were labelled by phycoerythrin-conjugated anti-TREM-1 monoclonal antibodies (R&D InC, Minneapolis, USA) for 30 minutes in the dark. nTREM-1 and mTREM-1 expression were assessed after passage of labelled cells through a flow cytometer (Epics XL/MSL, Beckman-Coulter Co, Miami Florida) and expressed as the mean fluorescence intensity (MFI) with gating for neutrophils and for monocytes by their characteristic FS/SS scattering.